Showing papers in "Journal of Strength and Conditioning Research in 2015"

Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.

Abstract: The purpose of this study was to compare the effect of low- versus high-load resistance training (RT) on muscular adaptations in well-trained subjects. Eighteen young men experienced in RT were matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a low-load RT routine (LL) where 25-35 repetitions were performed per set per exercise (n = 9) or a high-load RT routine (HL) where 8-12 repetitions were performed per set per exercise (n = 9). During each session, subjects in both groups performed 3 sets of 7 different exercises representing all major muscles. Training was performed 3 times per week on nonconsecutive days, for a total of 8 weeks. Both HL and LL conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups. Improvements in back squat strength were significantly greater for HL compared with LL (19.6 vs. 8.8%, respectively), and there was a trend for greater increases in 1 repetition maximum (1RM) bench press (6.5 vs. 2.0%, respectively). Upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively). These findings indicate that both HL and LL training to failure can elicit significant increases in muscle hypertrophy among well-trained young men; however, HL training is superior for maximizing strength adaptations.

Comparisons between low-intensity resistance training with blood flow restriction and high-intensity resistance training on quadriceps muscle mass and strength in elderly.

Abstract: High-intensity resistance training (HRT) has been recommended to offset age-related loss in muscle strength and mass. However, part of the elderly population is often unable to exercise at high intensities. Alternatively, low-intensity resistance training with blood flow restriction (LRT-BFR) has emerged. The purpose of this study was to compare the effects of LRT-BFR and HRT on quadriceps muscle strength and mass in elderly. Twenty-three elderly individuals, 14 men and 9 women (age, 64.04 ± 3.81 years; weight, 72.55 ± 16.52 kg; height, 163 ± 11 cm), undertook 12 weeks of training. Subjects were ranked according to their pretraining quadriceps cross-sectional area (CSA) values and then randomly allocated into one of the following groups: (a) control group, (b) HRT: 4 × 10 repetitions, 70-80% one repetition maximum (1RM), and (c) LRT-BFR: 4 sets (1 × 30 and 3 × 15 repetitions), 20-30% 1RM. The occlusion pressure was set at 50% of maximum tibial arterial pressure and sustained during the whole training session. Leg press 1RM and quadriceps CSA were evaluated at before and after training. A mixed-model analysis was performed, and the significance level was set at p ≤ 0.05. Both training regimes were effective in increasing pre- to post-training leg press 1RM (HRT: ∼54%, p < 0.001; LRT-BFR: ∼17%, p = 0.067) and quadriceps CSA (HRT: 7.9%, p < 0.001; LRT-BFR: 6.6%, p < 0.001); however, HRT seems to induce greater strength gains. In summary, LRT-BFR constitutes an important surrogate approach to HRT as an effective training method to induce gains in muscle strength and mass in elderly.

A comparison of methods for determining the rate of force development during isometric midthigh clean pulls.

Abstract: Twelve female division I collegiate volleyball players were recruited to examine the reliability of several methods for calculating the rate of force development (RFD) during the isometric midthigh clean pull All subjects were familiarized with the isometric midthigh clean pull and participated in regular strength training Two isometric midthigh clean pulls were performed with 2 minutes rest between each trail All measures were performed in a custom isometric testing device that included a step-wise adjustable bar and a force plate for measuring ground reaction forces The RFD during predetermined time zone bands (0-30, 0-50, 0-90, 0-100, 0-150, 0-200, and 0-250 milliseconds) was then calculated by dividing the force at the end of the band by the band's time interval The peak RFD was then calculated with the use of 2, 5, 10, 20, 30, and 50 milliseconds sampling windows The average RFD (avgRFD) was calculated by dividing the peak force (PF) by the time to achieve PF All data were analyzed with the use of intraclass correlation alpha (ICCα) and the coefficient of variation (CV) and 90% confidence intervals All predetermined RFD time bands were deemed reliable based on an ICCα >095 and a CV <4% Conversely, the avgRFD failed to meet the reliability standards set for this study Overall, the method used to assess the RFD during an isometric midthigh clean pull impacts the reliability of the measure and predetermined RFD time bands should be used to quantify the RFD

Long-Term Athletic Development- Part 1:a pathway for all youth

Abstract: The concept of developing talent and athleticism in youth is the goal of many coaches and sports systems. Consequently, an increasing number of sporting organizations have adopted long-term athletic development models in an attempt to provide a structured approach to the training of youth. It is clear that maximizing sporting talent is an important goal of long-term athletic development models. However, ensuring that youth of all ages and abilities are provided with a strategic plan for the development of their health and physical fitness is also important to maximize physical activity participation rates, reduce the risk of sport- and activity-related injury, and to ensure long-term health and well-being. Critical reviews of independent models of long-term athletic development are already present within the literature; however, to the best of our knowledge, a comprehensive examination and review of the most prominent models does not exist. Additionally, considerations of modern day issues that may impact on the success of any long-term athletic development model are lacking, as are proposed solutions to address such issues. Therefore, within this 2-part commentary, Part 1 provides a critical review of existing models of practice for long-term athletic development and introduces a composite youth development model that includes the integration of talent, psychosocial and physical development across maturation. Part 2 identifies limiting factors that may restrict the success of such models and offers potential solutions.

Mechanical Determinants of Faster Change of Direction and Agility Performance in Female Basketball Athletes

Abstract: Change of direction (COD) and agility require the integration of multiple components to produce a faster performance. However, the mechanisms contributing to a faster performance without the confounding factor of athlete expertise or gender is currently unknown. Therefore, the purpose of this study was to assess body composition, strength, and kinetic profile required for a faster COD and agility performance across multiple directional changes. Six faster and 6 slower (n 12) elite female basketball athletes completed a maximal dynamic back squat; eccentric and concentric only back squat; isometric midthigh pull; whole-body scan to determine lean, fat, and total mass; 505 COD test; T-test; and a multidirectional agility test over in-ground force plates to obtain relevant kinetic measures. Group (faster and slower) by test (2 × 3) multivariate analyses of variance with follow-up analyses of variance were conducted to examine differences between faster and slower groups and each COD and agility test (p ≤ 0.05). Faster athletes during the 505 COD test produced significantly greater vertical force (p 0.002) and eccentric and isometric strength capacity (p 0.001). Faster agility and T-test athletes demonstrated significantly shorter contact times (p 0.001), greater propulsive impulse (p 0.02), isometric strength, and relative lean mass compared with slower athletes. Differences between faster athletes across each test seem to be attributed to the mechanical demands of the directional change, increasing force and impulse application as the degree of directional change increased. These findings indicate that different mechanical properties are required to produce a faster COD and agility performances, and the importance of a greater strength capacity to enable greater mechanical adjustment through force production and body control, during different directional changes.

Effect of Vertical, Horizontal, and Combined Plyometric Training on Explosive, Balance, and Endurance Performance of Young Soccer Players.

Abstract: The aim of this study was to compare the effects of 6 weeks of vertical, horizontal, or combined vertical and horizontal plyometric training on muscle explosive, endurance, and balance performance. Forty young soccer players aged between 10 and 14 years were randomly divided into control (CG; n = 10), vertical plyometric group (VG; n = 10), horizontal plyometric group (HG; n = 10), and combined vertical and horizontal plyometric group (VHG; n = 10). Players performance in the vertical and horizontal countermovement jump with arms, 5 multiple bounds test (MB5), 20-cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV), sprint, change of direction speed (CODS), Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1), and balance was measured. No significant or meaningful changes in the CG, apart from small change in the Yo-Yo IR1, were observed while all training programs resulted in meaningful changes in explosive, endurance, and balance performance. However, only VHG showed a statistically significant (p ≤ 0.05) increase in all performance test and most meaningful training effect difference with the CG across tests. Although no significant differences in performance changes were observed between experimental groups, the VHG program was more effective compared with VG (i.e., jumps, MKV, sprint, CODS, and balance performance) and HG (i.e., sprint, CODS, and balance performance) to small effect. The study demonstrated that vertical, horizontal, and combined vertical and horizontal jumps induced meaningful improvement in explosive actions, balance, and intermittent endurance capacity. However, combining vertical and horizontal drills seems more advantageous to induce greater performance improvements.

Comparison of the Capacity of Different Jump and Sprint Field Tests to Detect Neuromuscular Fatigue

Abstract: Different jump and sprint tests have been used to assess neuromuscular fatigue, but the test with optimal validity remains to be established. The current investigation examined the suitability of vertical jump (countermovement jump [CMJ], squat jump [SJ], drop jump [DJ]) and 20-m sprint (SPRINT) testing for neuromuscular fatigue detection. On 6 separate occasions, 11 male team-sport athletes performed 6 CMJ, SJ, DJ, and 3 SPRINT trials. Repeatability was determined on the first 3 visits, with subsequent 3 visits (0-, 24-, and 72-hour postexercise) following a fatiguing Yo-Yo running protocol. SPRINT performance was most repeatable (mean coefficient of variation ≤2%), whereas DJ testing (4.8%) was significantly less repeatable than CMJ (3.0%) and SJ (3.5%). Each test displayed large decreases at 0-hour (33 of 49 total variables; mean effect size = 1.82), with fewer and smaller decreases at 24-hour postexercise (13 variables; 0.75), and 72-hour postexercise (19 variables; 0.78). SPRINT displayed the largest decreases at 0-hour (3.65) but was subsequently unchanged, whereas SJ performance recovered by 72-hour postexercise. In contrast, CMJ and DJ performance displayed moderate (12 variables; 1.18) and small (6 variables; 0.53) reductions at 72-hour postexercise, respectively. Consequently, the high repeatability and immediate and prolonged fatigue-induced changes indicated CMJ testing as most suitable for neuromuscular fatigue monitoring.

Plyometric Training Effects on Athletic Performance in Youth Soccer Athletes: A Systematic Review.

Abstract: The purpose of this systematic review was to critically analyze the literature to determine the effectiveness of plyometric training on athletic performance in youth soccer athletes. A total of 7 studies were included in this review after meeting the following criteria: (a) used plyometric training programs to assess athletic performance, (b) subjects were soccer athletes aged preadolescent up to 17 years, and (c) were published from 2000 to January 2014. Study methods were assessed using the PEDro scale with scores ranging from 4 to 6. Results showed similarities and differences in methodologies and procedures among the included studies. Athletic performance consisting of kicking distance, speed, jumping ability, and agility significantly improved because of plyometric training interventions. The current evidence suggests that plyometric training should be completed 2 days per week for 8-10 weeks during soccer practice with a 72-hour rest period between plyometric training days. The initial number of foot contacts should be 50-60 per session and increase to no more than 80-120 foot contacts per session for this age group to prevent overuse injuries. A total of 3-4 plyometric training exercises should be performed 2-4 sets for 6-15 repetitions per training session. The evidence and the literature suggest that plyometric training for this age group should only be implemented using recommended safety guidelines such as those published by the Canadian Society for Exercise Physiology and the National Strength and Conditioning Association and under appropriate supervision by trained personnel.

Effect of Unilateral, Bilateral, and Combined Plyometric Training on Explosive and Endurance Performance of Young Soccer Players

Abstract: The aim of the study was to compare the effects of bilateral, unilateral, or combined bilateral and unilateral plyometric training (PT) on muscle power output, endurance, and balance performance adaptations in young soccer players. Four groups of young soccer players (age 11.4 ± 2.2 years) were divided into control group (CG; n = 14), bilateral group (BG; n = 12), unilateral group (UG; n = 16), and bilateral + unilateral group (B + UG; n = 12). Players were measured in unilateral and bilateral countermovement jump with arms, 5 multiple bounds test, 20-cm drop jump reactive strength index, maximal kicking velocity, sprint and agility test time, endurance, and balance performance. The PT was applied during 6 weeks, 2 sessions per week, for a total of 2,160 jumps. After intervention, all PT groups showed a statistically significant (p ≤ 0.05) change in all performance measures, with no statistically significant differences between treatments. Among the 21 performance measures, the B + UG showed a significantly (p ≤ 0.05) higher performance change in 13 of them vs. the CG, whereas the UG and BG showed only 6 and 3, respectively. The current study showed that bilateral, unilateral, and combined bilateral and unilateral PT ensured significant improvement in several muscular power and endurance performance measures in young soccer players. However, the combination of unilateral and bilateral drills seems more advantageous to induce superior performance improvements.

Effect of intestinal microbiota on exercise performance in mice.

Abstract: The antioxidant enzyme system helps protect against intense exercise-induced oxidative damage and is related to the physical status of athletes. Evidence suggests that intestinal microbiota may be an important environmental factor associated with host metabolism, physiology, and antioxidant endogenous defense. However, evidence of the effect of gut microbiota status on exercise performance and physical fatigue is limited. We investigated the association of intestinal bacteria and exercise performance in specific pathogen-free (SPF), germ-free (GF), and Bacteroides fragilis (BF) gnotobiotic mice. Endurance swimming time was longer for SPF and BF than GF mice, and the weight of liver, muscle, brown adipose, and epididymal fat pads was higher for SPF and BF than GF mice. The serum levels of glutathione peroxidase (GPx) and catalase were greater in SPF than GF mice. Serum superoxide dismutase activity was lower in BF than SPF and GF mice. In addition, hepatic GPx level was higher in SPF than GF and BF mice. Gut microbial status could be crucial for exercise performance and its potential action linked with the antioxidant enzyme system in athletes.

Vertical and Horizontal Jump Tests Are Strongly Associated With Competitive Performance in 100-m Dash Events.

Abstract: Fourteen male elite sprinters performed short-distance sprints and jump tests until 18 days before 100-m dash competitions in track and field to determine if these tests are associated with 100-m sprint times. Testing comprised of squat jumps (SJ), countermovement jumps (CMJ), horizontal jumps (HJ), maximum mean propulsive power relative to body mass in loaded jump squats, and a flying start 50-m sprint. Moderate associations were found between speed tests and competitive 100-m times (r = 0.54, r = 0.61, and r = 0.66 for 10-, 30-, and 50-m, respectively, p ≤ 0.05). In addition, the maximum mean propulsive power relative to body mass was very largely correlated with 100-m sprinting performance (r = 0.75, p < 0.01). The correlations of SJ, CMJ, and HJ with actual 100-m sprinting times amounted to -0.82, -0.85, and -0.81, respectively. Because of their practicality, safeness, and relationship with the actual times obtained by top-level athletes in 100-m dash events, it is highly recommended that SJ, CMJ, and HJ be regularly incorporated into elite sprint-testing routines.

Postactivation potentiation of sprint acceleration performance using plyometric exercise.

Abstract: Postactivation potentiation (PAP), an acute and temporary enhancement of muscular performance resulting from previous muscular contraction, commonly occurs after heavy resistance exercise. However, this method of inducing PAP has limited application to the precompetition practices (e.g., warm-up) of many athletes. Very few studies have examined the influence of plyometric activity on subsequent performance; therefore, we aimed to examine the influence of alternate-leg bounding on sprint acceleration performance. In a randomized crossover manner, plyometric-trained men (n = 23) performed seven 20-m sprints (with 10-m splits) at baseline, ∼15 seconds, 2, 4, 8, 12, and 16 minutes after a walking control (C) or 3 sets of 10 repetitions of alternate-leg bounding using body mass (plyometric, P) and body mass plus 10% (weighted plyometric, WP). Mean sprint velocities over 10 and 20 m were similar between trials at baseline. At ∼15 seconds, WP impaired 20-m sprint velocity by 1.4 ± 2.5% when compared with C (p = 0.039). Thereafter, 10- and 20-m sprint velocities improved in WP at 4 minutes (10 m: 2.2 ± 3.1%, p = 0.009; 20 m: 2.3 ± 2.6%, p = 0.001) and 8 minutes (10 m: 2.9 ± 3.6%, p = 0.002; 20 m: 2.6 ± 2.8%, p = 0.001) compared with C. Improved 10-m sprint acceleration performance occurred in P at 4 minutes (1.8 ± 3.3%, p = 0.047) relative to C. Therefore, sprint acceleration performance is enhanced after plyometric exercise providing adequate recovery is given between these activities; however, the effects may differ according to whether additional load is applied. This finding presents a practical method to enhance the precompetition practices of athletes.

Systematic review and meta-analysis of linear and undulating periodized resistance training programs on muscular strength.

Abstract: Periodization is known to improve training adaptations but the most effective periodization approach for muscular strength development for a wide variety of populations is yet to be determined. This systematic review and meta-analysis examined all studies directly comparing linear and undulating periodized resistance training programs to determine and compare their effects on muscular strength. A systematic search of the MEDLINE, SCOPUS, and SPORTDiscus databases revealed 17 studies satisfying the inclusion criteria. There were a total of 510 participants in the included studies. Sixteen studies reported significant increases in strength for both periodization approaches. Five studies reported significant differences in improvements between groups. The meta-analyses determined that there were no differences in the effectiveness of linear vs. undulating periodization on upper-body or lower-body strength. The short-term nature of studies and the previous training history of participants were identified as potential confounding factors in the interpretation of findings. The results suggest that novelty or training variety are important for stimulating further strength development. Few studies have examined the effect of periodization approaches in adolescent or athletic populations.

A retrospective study on anthropometrical, physical fitness, and motor coordination characteristics that influence dropout, contract status, and first-team playing time in high-level soccer players aged eight to eighteen years.

Abstract: The goal of this article was twofold, and a 2-study approach was conducted. The first study aimed to expose the anthropometrical, physical performance, and motor coordination characteristics that influence dropout from a high-level soccer training program in players aged 8-16 years. The mixed-longitudinal sample included 388 Belgian youth soccer players who were assigned to either a "club group" or a "dropout group." In the second study, cross-sectional data of anthropometry, physical performance, and motor coordination were retrospectively explored to investigate which characteristics influence future contract status (contract vs. no contract group) and first-team playing time for 72 high-level youth soccer players (mean age = 16.2 years). Generally, club players outperformed their dropout peers for motor coordination, soccer-specific aerobic endurance, and speed. Anthropometry and estimated maturity status did not discriminate between club and dropout players. Contract players jumped further (p = 0.011) and had faster times for a 5-m sprint (p = 0.041) than no contract players. The following prediction equation explains 16.7% of the variance in future playing minutes in adolescent youth male soccer players: -2,869.3 + 14.6 × standing broad jump. Practitioners should include the evaluation of motor coordination, aerobic endurance, and speed performances to distinguish high-level soccer players further succeeding a talent development program and future dropout players, between 8 and 16 years. From the age of 16 years, measures of explosivity are supportive when selecting players into a future professional soccer career.

Anthropometric and Physical Profiles of English Academy Rugby Union Players

Abstract: The purpose of this study was to evaluate the anthropometric and physical characteristics of English regional academy rugby union players by age category (under 16s, under 18s and under 21s). Data were collected on 67 academy players at the beginning of the preseason period and comprised anthropometric (height, body mass, and sum of 8 skinfolds) and physical (5-, 10-, 20-, and 40-m sprint, acceleration, velocity, and momentum; agility 505; vertical jump; Yo-Yo intermittent recovery test level 1; 30-15 intermittent fitness test; absolute and relative 3 repetition maximum front squat, split squat, bench press, prone row, and chin; and isometric mid-thigh pull). One-way analysis of variance demonstrated significant increases across the 3 age categories (p ≤ 0.05) for height (e.g., 16s = 178.8 ± 7.1; 18s = 183.5 ± 7.2; 21s = 186.7 ± 6.61 cm), body mass (e.g., 16s = 79.4 ± 12.8; 18s = 88.3 ± 11.9; 21s = 98.3 ± 10.4 kg), countermovement jump height and peak power, sprint momentum, velocity, and acceleration; absolute, relative, and isometric (e.g., 16s = 2,157.9 ± 309.9; 18s = 2,561.3 ± 339.4; 21s = 3,104.5 ± 354.0 N) strength. Momentum, maximal speed, and the ability to maintain acceleration were all discriminating factors between age categories, suggesting that these variables may be more important to monitor rather than sprint times. These findings highlight that anthropometric and physical characteristics develop across age categories and provide comparative data for English Academy Rugby Union players.

Time-motion analysis of Italian elite women's basketball games: individual and team analyses.

Abstract: The aim of this study was to assess elite women's basketball game performance. Five elite women's games (3 Italian first division and 2 Euroleague) were analyzed for individual and team time-motion analyses. The individual analysis evaluated the players' movement patterns with particular focus on high-intensity activity (HIA), sprint activity, and repeated sprint events (RSEs). Team analysis included live time (LT), stoppage time (ST), and their ratio, transfer (TR) phases, and half court and full court actions. The frequency of occurrence of changes of activities was n = 576 ± 110, one every 2.56 seconds of LT. Total HIA was 8.5 ± 1.8% of LT and no significant differences between quarter periods were observed. In general, players performed linear sprints (48.3 ± 2.9%) over 1-5 m distance (56.8 ± 5.6%). The occurrence of RSE was 4.4 ± 1.7, with 58.6 ± 18.5% passive recovery between sprints. Team analysis showed no significant difference between games for LT and ST phases (ratio = 1.18 ± 0.25). For game analysis, LT and ST were 43.4 ± 7.8% and 51.1 ± 8.4%, respectively. A difference between games was found for half court actions (p < 0.01) and TR phases (p ≤ 0.05). Moreover, 1 TR and 2 TR were the most performed (45.3 and 23.9%) actions. These results encourage coaches to include repeated sprint ability with mainly linear and short sprints into a comprehensive training program.

Reliability and Validity of Tests to Assess Lower-Body Muscular Power in Children.

Abstract: The purpose of this study was to analyze the reliability and the criterion-related validity of several lower-body muscular power tests (i.e., standing long jump [SLJ], squat jump, countermovement jump, and Abalakov jump) in children aged 6-12 years. Three hundred sixty three healthy children (168 girls) agreed to participate in this study. All the lower-body muscular power tests were performed twice (7 days apart), whereas the 1 repetition maximum (1 RM) leg extension test was performed 2 days after the first session of testing. All the tests showed a high reliability (intertrial difference close to 0 and no significant differences between trials, all p > 0.05). The association between the lower-body muscular power tests and 1 RM leg extension test was high (all p < 0.001). The SLJ and the Abalakov jump tests showed the highest association with 1 RM leg extension test (R = 0.700, test result, weight, height, sex, and age were added in the model). The SLJ test can be a useful tool to assess lower-body muscular power in children when laboratory methods are not feasible because it is practical, time efficient, and low in cost and equipment requirements.

Relationship between sprint ability and loaded/unloaded jump tests in elite sprinters.

Abstract: The neuromechanical determinants of sprint running performance have been investigated in team sports athletes and non-elite sprinters. The aim of this study was to quantify the relationships between kinetic and performance parameters, obtained in loaded and unloaded vertical and horizontal jumps, and sprinting in elite athletes. Twenty-two sprinters performed squat jumps, countermovement jumps, horizontal jumps, and jump squats with different loads on a force platform, in addition to a 50-m sprint. Results indicated that jumping height and distance in vertical and horizontal jumps are more strongly correlated (R ≈ 0.81) to sprinting speed than the respective peak forces (R ≈ 0.36). Furthermore, the optimum load generating the maximum power in the jump squat is also highly correlated to sprint performance (R ≈ 0.72). These results reveal that vertical and horizontal jump tests may be used by coaches for assessing and monitoring qualities related to sprinting performance in elite sprinters.

Dose-response of 1, 3, and 5 sets of resistance exercise on strength, local muscular endurance, and hypertrophy.

Abstract: The study's purpose was to compare the response of performing 1, 3, and 5 sets on measures of performance and muscle hypertrophy. Forty-eight men, with no weight training experience, were randomly assigned to one of the 3 training groups, 1 SET, 3 SETS, 5 SETS, or control group. All training groups performed 3 resistance training sessions per week for 6 months. The 5 repetition maximum (RM) for all training groups increased in the bench press (BP), front lat pull down (LPD), shoulder press (SP), and leg press (LP) (p ≤ 0.05), with the 5 RM increases in the BP and LPD being significantly greater for 5 SETS compared with the other training groups (p ≤ 0.05). Bench press 20 RM in the 3-SET and 5-SET groups significantly increased with the increase being significantly greater than the 1-SET group and the 5-SET group increase being significantly greater than the 3-SET group (p ≤ 0.05). LP 20 RM increased in all training groups (p ≤ 0.05), with the 5-SETS group showing a significantly greater increase than the 1-SET group (p ≤ 0.05). The 3-SET and 5-SET groups significantly increased elbow flexor muscle thickness (MT) with the 5-SET increase being significantly greater than the other 2 training groups (p ≤ 0.05). The 5-SET group significantly increased elbow extensor MT with the increase being significantly greater than the other training groups (p ≤ 0.05). All training groups decreased percent body fat, increased fat-free mass, and vertical jump ability (p ≤ 0.05), with no differences between groups. The results demonstrate a dose-response for the number of sets per exercise and a superiority of multiple sets compared with a single set per exercise for strength gains, muscle endurance, and upper arm muscle hypertrophy.

Lower-extremity strength ratios of professional soccer players according to field position.

Abstract: Previous investigators have proposed that knee strength, hamstrings to quadriceps, and side-to-side asymmetries may vary according to soccer field positions. However, different results have been found in these variables, and a generalization of this topic could lead to data misinterpretation by coaches and soccer clubs. Thus, the aim of this study was to measure knee strength and asymmetry in soccer players across different field positions. One hundred and two male professional soccer players performed maximal concentric and eccentric isokinetic knee actions on the preferred and nonpreferred legs at a velocity of 60° · s. Players were divided into their field positions for analysis: goalkeepers, side backs, central backs, central defender midfielders, central attacking midfielders, and forwards. Results demonstrated that only goalkeepers (GK) differed from most other field positions on players' characteristics, and concentric peak torque across muscles. Although all players presented functional ratios of the preferred (0.79 ± 0.14) and nonpreferred (0.75 ± 0.13) legs below accepted normative values, there were no differences between positions for conventional or functional strength ratios or side-to-side asymmetry. The same comparisons were made only between field players, without inclusion of the GK, and no differences were found between positions. Therefore, the hamstrings to quadriceps and side-to-side asymmetries found here may reflect knee strength functional balance required for soccer skills performance and game demands across field positions. These results also suggest that isokinetic strength profiles should be considered differently in GK compared with other field positions due to their specific physiological and training characteristics.

The effect of an intervention program on functional movement screen test scores in mixed martial arts athletes.

Abstract: This study assessed the basic fundamental movements of mixed martial arts (MMA) athletes using the functional movement screen (FMS) assessment and determined if an intervention program was successful at improving results. Participants were placed into 1 of the 2 groups: intervention and control groups. The intervention group was required to complete a corrective exercise program 4 times per week, and all participants were asked to continue their usual MMA training routine. A mid-intervention FMS test was included to examine if successful results were noticed sooner than the 8-week period. Results highlighted differences in FMS test scores between the control group and intervention group (p = 0.006). Post hoc testing revealed a significant increase in the FMS score of the intervention group between weeks 0 and 8 (p = 0.00) and weeks 0 and 4 (p = 0.00) and no significant increase between weeks 4 and 8 (p = 1.00). A χ analysis revealed that the intervention group participants were more likely to have an FMS score >14 than participants in the control group at week 4 (χ = 7.29, p < 0.01) and week 8 (χ = 5.2, p ≤ 0.05). Finally, a greater number of participants in the intervention group were free from asymmetry at week 4 and week 8 compared with the initial test period. The results of the study suggested that a 4-week intervention program was sufficient at improving FMS scores. Most if not all, the movements covered on the FMS relate to many aspects of MMA training. The knowledge that the FMS can identify movement dysfunctions and, furthermore, the fact that the issues can be improved through a standardized intervention program could be advantageous to MMA coaches, thus, providing the opportunity to adapt and implement new additions to training programs.

Influence of Resistance Training Frequency on Muscular Adaptations in Well-Trained Men

Abstract: The purpose of this study was to investigate the effects of training muscle groups 1 day per week using a split-body routine (SPLIT) vs. 3 days per week using a total-body routine (TOTAL) on muscular adaptations in well-trained men. Subjects were 20 male volunteers (height = 1.76 ± 0.05 m; body mass = 78.0 ± 10.7 kg; age = 23.5 ± 2.9 years) recruited from a university population. Participants were pair matched according to baseline strength and then randomly assigned to 1 of the 2 experimental groups: a SPLIT, where multiple exercises were performed for a specific muscle group in a session with 2-3 muscle groups trained per session (n = 10) or a TOTAL, where 1 exercise was performed per muscle group in a session with all muscle groups trained in each session (n = 10). Subjects were tested pre- and poststudy for 1 repetition maximum strength in the bench press and squat, and muscle thickness (MT) of forearm flexors, forearm extensors, and vastus lateralis. Results showed significantly greater increases in forearm flexor MT for TOTAL compared with SPLIT. No significant differences were noted in maximal strength measures. The findings suggest a potentially superior hypertrophic benefit to higher weekly resistance training frequencies.

Effects of velocity-based resistance training on young soccer players of different ages.

Abstract: This study aimed to analyze the effect of velocity-based resistance training (RT) with moderate loads and few repetitions per set combined with jumps and sprints on physical performance in young soccer players of different ages. A total of 44 elite youth soccer players belonging to 3 teams participated in this study: an under-16 team (U16, n = 17) and an under-18 team (U18, n = 16) performed maximal velocity RT program for 26 weeks in addition to typical soccer training, whereas an under-21 team (U21, n = 11) did not perform RT. Before and after the training program, all players performed 20-m running sprint (T20), countermovement jump (CMJ), a progressive isoinertial loading test in squat to determine the load that elicited a ∼ 1 m · s(-1) velocity (V1LOAD) and an incremental field test to determine maximal aerobic speed (MAS). U16 showed significantly (p = 0.000) greater gains in V1LOAD than U18 and U21 (100/0/0%). Only U16 showed significantly (p = 0.01) greater gains than U21 (99/1/0%) in CMJ height. U18 obtained a likely better effect on CMJ performance than U21 (89/10/1%). The beneficial effects on T20 between groups were unclear. U16 showed a likely better effect on MAS than U21 (80/17/3%), whereas the rest of comparisons were unclear. The changes in CMJ correlated with the changes in T20 (r = -0.49) and V1LOAD (r = 0.40). In conclusion, velocity-based RT with moderate load and few repetitions per set seems to be an adequate method to improve physical performance in young soccer players.

Long-term athletic development, part 2: barriers to success and potential solutions.

Abstract: The first installment of this two-part commentary reviewed existing models of long-term athletic development. However, irrespective of the model that is adopted by practitioners, existing structures within competitive youth sports in addition to the prevalence of physical inactivity in a growing number of modern-day youth may serve as potential barriers to the success of any developmental pathway. The second part of this commentary will initially highlight common issues that are likely to impede the success of long-term athletic development programs and then propose solutions that will address the negative impact of such issues.

Comparison of Total and Segmental Body Composition Using Dxa and Multifrequency Bioimpedance in Collegiate Female Athletes

Abstract: The purpose of this investigation was to determine the agreement between multifrequency bioelectrical impedance analysis (BIA) and dual-energy x-ray absorptiometry (DXA) for measuring body fat percentage (BF%), fat-free mass (FFM), and total body and segmental lean soft tissue (LST) in collegiate female athletes. Forty-five female athletes (age = 21.2 ± 2.0 years, height = 166.1 ± 7.1 cm, weight = 62.6 ± 9.9 kg) participated in this study. Variables measured through BIA and DXA were as follows: BF%, FFM, and LST of the arms (ARMS(LST)), the legs (LEGS(LST)), the trunk (TRUNK(LST)), and the total body (TOTAL(LST)). Compared with the DXA, the InBody 720 provided significantly lower values for BF% (-3.3%, p < 0.001) and significantly higher values for FFM (2.1 kg, p < 0.001) with limits of agreement (1.96 SD of the mean difference) of ±5.6% for BF% and ±3.7 kg for FFM. No significant differences (p < 0.008) existed between the 2 devices (InBody 720-DXA) for ARMS(LST) (0.05 kg), TRUNK(LST) (0.14 kg), LEGS(LST) (-0.4 kg), and TOTAL(LST) (-0.21 kg). The limits of agreement were ±0.79 kg for ARMS(LST), ±2.62 kg for LEGS(LST), ±3.18 kg for TRUNK(LST), and ±4.23 kg for TOTAL(LST). This study found discrepancies in BF% and FFM between the 2 devices. However, the InBody 720 and DXA appeared to provide excellent agreement for measuring total body and segmental LST. Therefore, the InBody 720 may be a rapid noninvasive method to assess LST in female athletes when DXA is not available.

Physical qualities predict change-of-direction speed but not defensive agility in Australian rules football.

Abstract: The purpose of this study was to determine the relationships between selected physical qualities, change-of-direction (COD) speed, and defensive agility performance in Australian Rules football players. Twenty-four male community-level players were assessed on sprint acceleration (10-m time), maximum strength (3 repetition-maximum half squat), leg power (countermovement jump), reactive strength (drop jump), and a single COD speed test and a defensive agility test. Change-of-direction speed was correlated with reactive strength (r = -0.645, p = 0.001) and sprint acceleration (r = 0.510, p = 0.011). Multiple regression indicated that the combined physical qualities explained 56.7% of the variance associated with COD speed (adjusted R = 0.567, p ≤ 0.05). Participants were median split into faster and slower COD speed groups, and these were compared by independent t-tests. The faster group was significantly better (p ≤ 0.05) on the sprint acceleration and reactive strength tests (large effect size). The correlations between physical qualities and agility were trivial to small (r = -0.101 to 0.123, p > 0.05) and collectively explained only 14.2% of the variance associated with agility performance (adjusted R = -0.142, p > 0.05). When faster and slower agility groups were compared, there were trivial to moderate differences (p > 0.05) in all physical qualities. It was concluded that reactive strength and sprint acceleration are important for COD speed, but the physical qualities assessed are not associated with defensive agility performance. For agility tasks similar to those in this study, sprint and resistance training should not be emphasized, and training other factors, such as the development of sport-specific technique and cognitive skill, is recommended.

Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level.

Abstract: Vertical jump (VJ) performance is an important element for successful volleyball practice. The aims of the study were (a) to explore the overall VJ performance of elite volleyball players of both sexes, (b) to explore the differences in VJ performance among different competition levels and different playing positions, and (c) to evaluate the sex-related differences in the role of the arm swing and 3-step approach with arm swing on the jump height. We assessed the VJ capacity in 253 volleyball players (113 males and 140 females) from Slovenian first and second Volleyball Division. The height of squat jump (SJ), countermovement jump, block jump, and attack jump was tested using an Optojump system. We observed significant differences (p ≤ 0.05) in VJ height between different levels of play that were most pronounced in the SJ. Position-related differences in VJ performance were observed in male players between receivers and setters (p ≤ 0.05), whereas in females, VJ performance across different playing positions seems equal. Finally, we found that male players significantly better use the arm swing during VJ than females (p ≤ 0.05), whereas the use of eccentric part of the jump and approach before the spike to improve VJ performance seem to be equally mastered activity in both sexes. These results could assist coaches in the development of jumping performance in volleyball players. Furthermore, presented normative data for jump heights of elite male and female volleyball players could be useful in selection and profiling of young volleyball players.

Effects of Plyometric and Sprint Training on Physical and Technical Skill Performance in Adolescent Soccer Players.

Abstract: To determine the influence of a short-term combined plyometric and sprint training (9 weeks) within regular soccer practice on explosive and technical actions of pubertal soccer players during the in-season. Twenty-six players were randomly assigned to 2 groups: control group (CG) (soccer training only) and combined group (CombG) (plyometric + acceleration + dribbling + shooting). All players trained soccer 4 times per week and the experimental groups supplemented the soccer training with a proposed plyometric-sprint training program for 40 minutes (2 days per weeks). Ten-meter sprint, 10-m agility with and without ball, CMJ and Abalakov vertical jump, ball-shooting speed, and Yo-Yo intermittent endurance test were measured before and after training. The experimental group followed a 9-week plyometric and sprint program (i.e., jumping, hurdling, bouncing, skipping, and footwork) implemented before the soccer training. Baseline-training results showed no significant differences between the groups in any of the variables tested. No improvement was found in the CG; however, meaningful improvement was found in all variables in the experimental group: CMJ (effect size [ES] = 0.9), Abalakov vertical jump (ES = 1.3), 10-m sprint (ES = 0.7-0.9), 10-m agility (ES = 0.8-1.2), and ball-shooting speed (ES = 0.7-0.8). A specific combined plyometric and sprint training within regular soccer practice improved explosive actions compared with conventional soccer training only. Therefore, the short-term combined program had a beneficial impact on explosive actions, such as sprinting, change of direction, jumping, and ball-shooting speed which are important determinants of match-winning actions in soccer performance. Therefore, we propose modifications to current training methodology for pubertal soccer players to include combined plyometric and speed training for athlete preparation in this sport.

Heart Rate–Based Training Intensity and Its Impact on Injury Incidence Among Elite-Level Professional Soccer Players

Abstract: Elite-level professional soccer players are suggested to have increased physical, technical, tactical, and psychological capabilities when compared with their subelite counterparts. Ensuring these players remain at the elite level generally involves training many different bodily systems to a high intensity or level within a short duration. This study aimed to examine whether an increase in training volume at high-intensity levels was related to injury incidence, or increased the odds of sustaining an injury. Training intensity was monitored through time spent in high-intensity (T-HI) and very high-intensity (T-VHI) zones of 85-<90% and ≥90% of maximal heart rate (HRmax), and all injuries were recorded over 2 consecutive seasons. Twenty-three, elite professional male soccer players (mean ± SD age, 25.6 ± 4.6 years; stature, 181.8 ± 6.8 cm; and body mass, 79.3 ± 8.1 kg) were studied throughout the 2-years span of the investigation. The results showed a mean total injury incidence of 18.8 (95% confidence interval [CI], 14.7-22.9) injuries per 1,000 hours of exposure. Significant correlations were found between training volume at T-HI and injury incidence (r = 0.57, p = 0.005). Further analysis revealed how players achieving more time in the T-VHI zone during training increased the odds of sustaining a match injury (odds ratio = 1.87; 95% CI, 1.12-3.12, p = 0.02) but did not increase the odds of sustaining a training injury. Reducing the number of competitive match injuries among elite-level professional players may be possible if greater focus is placed on the training intensity and volume over a period of time ensuring the potential reduction of fatigue or overuse injuries. In addition, it is important to understand the optimal training load at which adaptation occurs without raising the risk of injury.

Improving Fitness of Elite Handball Players: Small-Sided Games vs. High-Intensity Intermittent Training

Abstract: The present study was designed to compare the effects of high-intensity intermittent training (HIIT) and small-sided games (SSGs) training on fitness variables of elite handball players. Eighteen highly trained players (mean age ± SD: 25.6 ± 0.5 years) were assigned to either HIIT or SSGs group training protocols twice per week for 8 weeks. The HIIT consisted of 12-24 × 15 seconds of high-intensity runs interspersed by 15 seconds of recovery. The SSGs training consisted of 3 against 3 small-sided handball games. Both training methods were matched for exercise duration and recovery at each training session. Before and after 8-week training, the following fitness variables were assessed-speed: 10- and 20-m sprint time, agility: handball agility specific test (HAST), upper arm strength: 1 repetition maximum (1RM) bench press test, lower limb power: counter-movement jump tests with (CMJarm) and without (CMJ) arm movement, and aerobic fitness (yo-yo intermittent recovery test level 1 [YYIRTL1]). Significant improvement was found in the YYIRTL1 (23.3 and 26.3%, respectively), 10-m sprint (2.3 and 4.1%, respectively) and 20-m sprint (2.1 and 4%, respectively), HAST (1.1 and 2.2%, respectively), 1RM bench press (6.8 and 12.3%, respectively), CMJ (7.4 and 10.8%, respectively), and CMJarm (6.4 and 8.9%, respectively) following training in both groups (p ≤ 0.05 for all). There was a significantly greater improvement in 10- and 20-m sprint, HAST, 1RM, CMJ, and CMJarm following the SSGs training compared with the HIIT (p ≤ 0.05 for all). These results indicated that both HIIT and SSGs are effective training methods for fitness development among elite adult handball players. However, SSGs training may be considered as the preferred training regimen for improving handball-specific fitness variables during the in-season period.