Showing papers in "Medicine and Science in Sports and Exercise in 2002"
TL;DR: In order to stimulate further adaptation toward a specific training goal(s), progression in the type of resistance training protocol used is necessary and emphasis should be placed on multiple-joint exercises, especially those involving the total body.
Abstract: In order to stimulate further adaptation toward a specific training goal(s), progression in the type of resistance training protocol used is necessary. The optimal characteristics of strength-specific programs include the use of both concentric and eccentric muscle actions and the performance of both single- and multiple-joint exercises. It is also recommended that the strength program sequence exercises to optimize the quality of the exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher intensity before lower intensity exercises). For initial resistances, it is recommended that loads corresponding to 8-12 repetition maximum (RM) be used in novice training. For intermediate to advanced training, it is recommended that individuals use a wider loading range, from 1-12 RM in a periodized fashion, with eventual emphasis on heavy loading (1-6 RM) using at least 3-min rest periods between sets performed at a moderate contraction velocity (1-2 s concentric, 1-2 s eccentric). When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number. The recommendation for training frequency is 2-3 d x wk(-1) for novice and intermediate training and 4-5 d x wk(-1) for advanced training. Similar program designs are recommended for hypertrophy training with respect to exercise selection and frequency. For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion, with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity. Higher volume, multiple-set programs are recommended for maximizing hypertrophy. Progression in power training entails two general loading strategies: 1) strength training, and 2) use of light loads (30-60% of 1 RM) performed at a fast contraction velocity with 2-3 min of rest between sets for multiple sets per exercise. It is also recommended that emphasis be placed on multiple-joint exercises, especially those involving the total body. For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (> 15) using short rest periods (< 90 s). In the interpretation of this position stand, as with prior ones, the recommendations should be viewed in context of the individual's target goals, physical capacity, and training status.
2,845 citations
TL;DR: There remains a need to better understand environmental influences and the factors that influence different types of PA and longitudinal and intervention studies will be required if causal relationships are to be inferred.
Abstract: Purpose To review and update the evidence relating to the personal, social, and environmental factors associated with physical activity (PA) in adults. Methods Systematic review of the peer-reviewed literature to identify papers published between 1998 and 2000 with PA (and including exercise and exercise adherence). Qualitative reports or case studies were not included. Results Thirty-eight new studies were located. Most confirmed the existence of factors already known to be correlates of PA. Changes in status were noted in relation to the influence of marital status, obesity, smoking, lack of time, past exercise behavior, and eight environmental variables. New studies were located which focused on previously understudied population groups such as minorities, middle and older aged adults, and the disabled. Conclusion The newly reported studies tend to take a broader “ecological” approach to understanding the correlates of PA and are more focused on environmental factors. There remains a need to better understand environmental influences and the factors that influence different types of PA. As most of the work in this field still relies on cross-sectional studies, longitudinal and intervention studies will be required if causal relationships are to be inferred.
2,730 citations
TL;DR: Although the cross-validation meets statistical standards for acceptance, caution is warranted with regard to implementation and it is recommended that maturity offset be considered as a categorical rather than a continuous assessment.
Abstract: Purpose: The range of variability between individuals of the same chronological age (CA) in somatic and biological maturity is large and especially accentuated around the adolescent growth spurt. Maturity assessment is an important consideration when dealing with adolescents, from both a research perspective and youth sports stratification. A noninvasive, practical method predicting years from peak height velocity (a maturity offset value) by using anthropometric variables is developed in one sample and cross-validated in two different samples. Methods: Gender specific multiple regression equations were calculated on a sample of 152 Canadian children aged 8-16 yr (79 boys; 73 girls) who were followed through adolescence from 1991 to 1997, The equations included three somatic dimensions (height, sitting height, and leg length), CA, and their interactions. The equations were cross-validated on a Combined sample of Canadian (71 boys, 40 girls measured from 1964 through 1973) and Flemish children (50 boys, 48 girls measured from 1985 through 1999). Results: The coefficient of determination (R2) for the boys' model was 0.92 and for the girls' model 0.91 the SEEs were 0.49 and 0.50, respectively, Mean difference between actual and predicted maturity offset for the verification samples was 0.24 (SD 0.65) yr in boys and 0,001 (SD 0.68) yr in girls. Conclusion: Although the cross-validation meets statistical standards or acceptance, caution 1, warranted with regard to implementation. It is recommended that maturity offset be considered as a categorical rather than a continuous assessment. Nevertheless, the equations presented are a reliable, noninvasive and a practical solution for the measure of biological maturity for matching adolescent athletes.
1,791 citations
TL;DR: In this paper, the authors evaluated age and gender differences in objectively measured physical activity (PA) in a population-based sample of students in grades 1-12 and found that PA declines rapidly during childhood and adolescence.
Abstract: TROST. S. G., R. R. PATE, J. F. SALLIS, P. S. FREEDSON, W. C. TAYLOR, M. DOWDA, and J. SIRARD. Age and gender differences in objectively measured physical activity in youth. Med. Sci. Sports Ererc., Vol. 34, No. 2, pp. 350-355, 2002. Purpose: The purpose of this study was to evaluate age and gender differences in objectively measured physical activity (PA) in a population-based sample of students in grades 1-12. Methods: Participants (185 male, 190 female) wore a CSA 7164 accelerometer for 7 consecutive days. To examine age-related trends. students were grouped as follows: grades 1-3 (N = 90), grades 4-6 (N = 91), grades 7-9 (N = 96). and grades 10-12 (N = 92). Bouts of PA and minutes spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) were examined. Results: Daily MVPA and VPA exhibited a significant inverse relationship with grade level, with the largest differences occurring between grades 1d-3 and 4-6. Boys were more active than girls; however, for overall PA, the magnitudes of the gender differences were modest. Participation in continuous 20-min bouts of PA was low to nonexistent. Conclusion: Our results support the notion that PA declines rapidly during childhood and adolescence and that accelerometers are feasible alternatives to self-report methods in moderately sized population-level surveillance studies.
1,490 citations
TL;DR: Findings provide insight for understanding the behavioral variability in the activity patterns of adults and suggest that reliable measures of activity behaviors require at least 7 d of monitoring.
Abstract: MATTHEWS, C. E., B. E. AINSWORTH, R. W. THOMPSON, and D. R. BASSETT, JR. Sources of variance in daily physical activity levels as measured by an accelerometer. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1376–1381, 2002.PurposeTo examine sources of variance in objective measures of physical
579 citations
TL;DR: It is concluded that a protocol with 3-min stages and 35-W increments in work rate can be used to determine Fat(max).
Abstract: ACHTEN, J., M. GLEESON, and A. E. JEUKENDRUP. Determination of the exercise intensity that elicits maximal fat oxidation. Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 92–97.PurposeThe aim of this study was to develop a test protocol to determine the exercise intensity at which fat oxidation ra
515 citations
TL;DR: Differences in mean steps per day detected may be due to differences in set instrument sensitivity thresholds and/or attachment, and additional studies with different populations are needed to confirm a recommended number of Steps per day associated with the duration and intensity of public health recommendations for ambulatory activity.
Abstract: Purpose: The purpose of this investigation was 1) to evaluate agreement between dual-mode CSA accelerometer outputs and Yamax pedometer outputs assessed concurrently under free-living conditions; 2) to determine the relationship between pedometer-steps per day and CSA-time spent in inactivity and in light-, moderate-, and vigorous-intensity activities; and 3) to identify a value of pedometer-steps per day that corresponds with a minimum of 30 CSA-min[middle dot]d-1 of moderate ambulatory activity. Methods: Data were analyzed from 52 participants (27 men, 25 women; mean age = 38.2 +/- 12.0 yr; mean BMI = 26.4 +/- 4.5 kg[middle dot]m-2) who were enrolled in the International Physical Activity Questionnaire study and wore both motion sensors during waking hours for 7 consecutive days. Results: Participants averaged 415.0 +/- 159.5 CSA-counts[middle dot]min-1[middle dot]d-1, 357,601 +/- 138,425 CSA-counts[middle dot]d-1, 11,483 +/- 3,856 CSA-steps[middle dot]d-1, and 9,638 +/- 4,030 pedometer-steps[middle dot]d-1. There was a strong relationship between all CSA outputs and pedometer outputs (r = 0.74-0.86). The mean difference in steps detected between instruments was 1845 +/- 2116 steps[middle dot]d-1 (CSA > pedometer; t = 6.29, P 0.80) in mean CSA-time (min[middle dot]d-1) in moderate and vigorous activity with increasing pedometer-determined activity quartiles; no differences were noted for inactivity or light activity. Approximately 33 CSA-min[middle dot]d-1 of moderate activity corresponded with 8000 pedometer-steps[middle dot]d-1. Conclusion: Differences in mean steps per day detected may be due to differences in set instrument sensitivity thresholds and/or attachment. Additional studies with different populations are needed to confirm a recommended number of steps per day associated with the duration and intensity of public health recommendations for ambulatory activity. (C) 2002 Lippincott Williams & Wilkins, Inc.
407 citations
TL;DR: In sprint running the spring-like behavior of the leg might be adjusted by changing the stiffness of the knee joint, which may depend on (constant) tendon stiffness because of its dominating role in triceps surae muscle-tendon unit.
Abstract: KUITUNEN, S., P. V. KOMI, and H. KYROLAINEN. Knee and ankle joint stiffness in sprint running. Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 166–173.IntroductionStiffness has often been considered as a regulated property of the neuromuscular system. The purpose of this study was to examine the
390 citations
TL;DR: The 4-month whole body vibration-intervention enhanced jumping power in young adults, suggesting neuromuscular adaptation to the vibration stimulus, and showed no effect on dynamic or static balance of the subjects.
Abstract: TORVINEN, S., P. KANNUS, H. SIEVANEN, T. A. JARVINEN, M. PASANEN, S. KONTULAINEN, T. L. JARVINEN, M. JARVINEN, P. OJA, and I. VUORI. Effect of four-month vertical whole body vibration on performance and balance. Med. Sci. Sports Exerc., Vol. 34, No. 9, pp. 1523-1528, 2002. Purpose: This randomized controlled study was designed to investigate the effects of a 4-month whole body vibration-intervention on muscle performance and body balance in young, healthy, nonathletic adults. Methods: Fifty-six volunteers (21 men and 35 women, aged 19 -38 yr) were randomized to either the vibration group or control group. The vibration-intervention consisted of a 4-month whole body vibration training (4 min·d 1 , 3-5 times a week) employed by standing on a vertically vibrating platform. Five performance tests (vertical jump, isometric extension strength of the lower extremities, grip strength, shuttle run, and postural sway on a stability platform) were performed initially and at 2 and 4 months. Results: Four-month vibration intervention induced an 8.5% (95% CI, 3.7-13.5%, P 0.001) net improvement in the jump height. Lower-limb extension strength increased after the 2-month vibration-intervention resulting in a 3.7% (95% CI, 0.3-7.2%, P 0.034) net benefit for the vibration. This benefit, however, diminished by the end of the 4-month intervention. In the grip strength, shuttle run, or balance tests, the vibration-intervention showed no effect. Conclusion: The 4-month whole body vibration-intervention enhanced jumping power in young adults, suggesting neuromuscular adaptation to the vibration stimulus. On the other hand, the vibration-intervention showed no effect on dynamic or static balance of the subjects. Future studies should focus on comparing the performance-enhancing effects of a whole body vibration to those of conventional resistance training and, as a broader objective, on investigating the possible effects of
373 citations
TL;DR: unique glenohumeral joint rotational patterning in unilaterally dominant upper extremity athletes that has ramifications for rehabilitation after injury and for both injury prevention and performance enhancement is identified.
Abstract: ELLENBECKER, T. S., E. P. ROETERT, D. S. BAILIE, G. J. DAVIES, and S. W. BROWN. Glenohumeral joint total rotation range of motion in elite tennis players and baseball pitchers. Med. Sci. Sports Exerc., Vol. 34, No. 12, pp. 2052–2056, 2002. The amount of glenohumeral joint internal and external rotation used during overhead sport activities has been measured experimentally by sports scientists. Clinical measurement of glenohumeral joint internal and external rotation using goniometry is an integral part of a shoulder evaluation after injury or surgery or during preseason or preventative musculoskeletal screenings. Purpose: This study measured glenohumeral joint internal and external rotation in two groups of unilaterally dominant upper extremity athletes to compare the total arc of rotational range of motion between the dominant and nondominant extremities. Methods: A total of 163 elite athletes (117 male junior tennis players and 46 male baseball pitchers) were measured for glenohumeral joint internal and external rotation at 90° of abduction. Total rotation range of motion was calculated by summing internal and external rotation measures in each extremity. Results: An ANOVA with post hoc testing revealed no significant difference ( P 0.05) between extremities in baseball pitchers for total rotation range of motion (145.7 vs 146.9), whereas significantly less ( P 0.001) dominant arm total rotation range of motion was identified in the elite junior tennis players (149.1 vs 158.2). Conclusion: This study has identified unique glenohumeral joint rotational patterning in unilaterally dominant upper extremity athletes that has ramifications for rehabilitation after injury and for both injury prevention and performance enhancement. Key Words: SHOULDER, GONIOMETRY, EXTERNAL ROTATION, INTERNAL ROTATION
315 citations
TL;DR: The results indicated no significant advantage of core strengthening in reducing LBP occurrence, though this may be more a reflection of the small numbers of subjects who actually required treatment, than the need for a larger scale study.
Abstract: NADLER, S. F., G. A. MALANGA, L. A. BARTOLI, J. H. FEINBERG, M. PRYBICIEN, and M. DEPRINCE. Hip muscle imbalance and low back pain in athletes: influence of core strengthening. Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 9‐16. Purpose: The influence of a core-strengthening program on low back pain (LBP) occurrence and hip strength differences were studied in NCAA Division I collegiate athletes. Methods: In 1998, 1999, and 2000, hip strength was measured during preparticipation physical examinations and occurrence of LBP was monitored throughout the year. Following the 1999‐2000 preparticipation physicals, all athletes began participation in a structured core-strengthening program, which emphasized abdominal, paraspinal, and hip extensor strengthening. Incidence of LBP and the relationship with hip muscle imbalance were compared between consecutive academic years. Results: After incorporation of core strengthening, there was no statistically significant change in LBP occurrence. Side-to-side extensor strength between athletes participating in both the 1998‐1999 and 1999‐2000 physicals were no different. After core strengthening, the right hip extensor was, on average, stronger than that of the left hip extensor (P ! 0.0001). More specific gender differences were noted after core strengthening. Using logistic regression, female athletes with weaker left hip abductors had a more significant probability of requiring treatment for LBP (P ! 0.009) Conclusion: The impact of core strengthening on collegiate athletes has not been previously examined. These results indicated no significant advantage of core strengthening in reducing LBP occurrence, though this may be more a reflection of the small numbers of subjects who actually required treatment. The core program, however, seems to have had a role in modifying hip extensor strength balance. The association between hip strength and future LBP occurrence, observed only in females, may indicate the need for more gender-specific core programs. The need for a larger scale study to examine
TL;DR: Water-based exercise appears to be a very safe and beneficial mode of exercise that can be performed as part of a well-rounded exercise program in older adult women.
Abstract: TAKESHIMA, N., M. E. ROGERS, E. WATANABE, W. F. BRECHUE, A. OKADA, T. YAMADA, M. M. ISLAM, and J. HAYANO. Water-based exercise improves health-related aspects of fitness in older women. Med. Sci. Sports Exerc., Vol. 33, No. 3, pp. 544–551, 2002.PurposeThe purpose of this study was to determine the p
TL;DR: Results are consistent with the hypothesis that increased patellofemoral joint stress may be a predisposing factor with respect to development of PFP and indicate that treatments designed to increase the area of contact between the patella and the femur may be beneficial in reducing the PFJ stress during functional activities.
Abstract: BRECHTER, J. H., and C. M. POWERS. Patellofemoral stress during walking in persons with and without patellofemoral pain. Med. Sci. Sports Exerc., Vol. 34, No. 10, pp. 1582–1593, 2002.ObjectiveTo determine whether individuals with patellofemoral pain (PFP) demonstrate elevated patellofemoral joint (P
TL;DR: Low- and moderate-intensity aerobic-exercise programs were equally effective in improving physiological and psychological function in this population of cancer survivors and aerobic exercise appears to be a valuable and well-tolerated component of the cancer-rehabilitation process.
Abstract: BURNHAM, T. R., and A. WILCOX. Effects of exercise on physiological and psychological variables in cancer survivors. Med. Sci. Sports Exerc., Vol. 34, No. 12, pp. 1863–1867, 2002.PurposeThe primary purpose of this study was to examine the effect of aerobic exercise on physiological and psych
TL;DR: Examination of the influence of a concurrent HWT+endurance training on CR and the .VO(2) kinetics in endurance athletes found additional HWT led to improved maximal strength and running economy with no significant effects on the .
Abstract: MILLET, G. P., B. JAOUEN, F. BORRANI, and R. CANDAU. Effects of concurrent endurance and strength training on running economy and VO2 kinetics. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1351-1359. 2002. Purpose: It has been suggested that endurance training influences the running economy (CR) and the oxygen uptake (VO2 ) kinetics in heavy exercise by accelerating the primary phase and attenuating the VO2 slow component. However, the effects of heavy weight training (HWT) in combination with endurance training remain unclear. The purpose of this study was to examine the influence of a concurrent HWT+ endurance training on CR and the VO2 kinetics in endurance athletes. Methods: Fifteen triathletes were assigned to endurance+strength (ES) or endurance-only (E) training for 14 wk. The training program was similar, except ES performed two HWT sessions a week. Before and after the training period, the subjects performed 1) an incremental field running test for determination of VO2,_ and the velocity associated (V402m.), the second ventilatory threshold (VT2): 2) a 3000-m run at constant velocity, calculated to require 25% of the difference between VO2 m,, and VT2 to determine CR and the characteristics of the VO2 kinetics; 3) maximal hopping tests to determine maximal mechanical power and lower-limb stiffness; 4) maximal concentric lower-limb strength measurements. Results: After the training period, maximal strength were increased (P < 0.01) in ES but remained unchanged in E. Hopping power decreased in E (P < 0.05). After training, economy (P < 0.05) and hopping power (P < 0.001) were greater in ES than in E. VO2 m_,,, leg hopping stiffness and the VO2 kinetics were not significantly affected by training either in ES or E. Conclusion: Additional HWT led to improved
TL;DR: Findings indicate 3-d x wk(-1) concurrent performance of both strength and endurance training does not impair adaptations in strength, muscle hypertrophy, and neural activation induced by strength training alone.
Abstract: McCARTHY, J. P., M. A. POZNIAK, and J. C. AGRE. Neuromuscular adaptations to concurrent strength and endurance training. Med. Sci. Sports Exerc., Vol. 34, No. 3, pp. 511–519, 2002.PurposeThe purpose of this study was to examine muscle morphological and neural activation adaptations resulting from th
TL;DR: The altered kinematics may have resulted in increased metabolic costs during the latter stages of the exhaustive run, and the increase in peak impact accelerations at the leg was not considered an increased injury risk because of the decreased effective mass.
Abstract: DERRICK, T. R., D. DEREU, and S. P. MCLEAN. Impacts and kinematic adjustments during an exhaustive run.Med. Sci. Sports Exerc., Vol. 34, No. 6, pp. 998 –1002, 2002. Purpose: To examine the kinematic adjustments that runners make during an exhaustive run and to look at the effects these adjustments have on shock and shock attenuation. Methods: Ten recreational runners ran to volitional exhaustion on a treadmill at a velocity equal to their average 3200-m running velocity at maximal effort (average time: 15.7 1.7 min). Head and leg accelerometers, a knee electrogoniometer, and a rearfoot electrogoniometer were attached to each subject. The data were sampled at 1000 Hz at the start, middle, and end of the run. Results: The knee became significantly more flexed at heel impact (start: 164.9 2.3°; end: 160.5 2.9°; P 0.05). The rearfoot angle became more inverted at impact (start: 12.2 1.6°; end: 13.6 1.9°; P 0.05). These kinematic changes resulted in a lower extremity that that had a lower effective mass during the impact. This decreased effective mass allowed the leg to accelerate more easily; thus, peak leg impact accelerations (start: 6.11 0.96 g; end: 7.38 1.05 g; P 0.05) and impact attenuation (start: 74.5 5.4%; end: 77.5 4.1%; P 0.05) increased during the progression of the run. Conclusions: The increase in peak impact accelerations at the leg was not considered an increased injury risk because of the decreased effective mass. The altered kinematics may have resulted in increased metabolic costs during the latter stages of the
TL;DR: Data support the hypothesis that moderate levels of physical activity are associated with a reduced risk for URTI and this effect was stronger in men than women.
Abstract: MATTHEWS, C. E., I. S. OCKENE, P. S. FREEDSON, M. C. ROSAL, P. A. MERRIAM, and J. R. HEBERT. Moderate to vigorous physical activity and risk of upper-respiratory tract infection. Med. Sci. Sports Exerc., Vol. 34, No. 8, pp. 1242–1248, 2002.PurposeA “J”-shaped model has been proposed to descr
TL;DR: It is suggested that three short bouts (10 min) of brisk walking accumulated throughout the day are at least as effective as one continuous bout of equal total duration in reducing cardiovascular risk and improving aspects of mood in previously sedentary individuals.
Abstract: MURPHY, M., A. NEVILL, C. NEVILLE, S. BIDDLE, and A. HARDMAN. Accumulating brisk walking for fitness, cardiovascular risk, and psychological health. Med. Sci. Sports Exerc., Vol. 34, No. 9, pp. 1468–1474, 2002. Purpose: To compare the effects of different patterns of regular brisk walking on fitness, risk factors for cardiovascular disease, and psychological well-being in previously sedentary adults. Methods: Twenty-one subjects (14 women), aged 44.5 ± 6.1 yr (mean ± SD) were randomly assigned to two different, 6-wk programs of brisk walking in a cross-over design, with an interval of 2 wk. One program comprised one 30-min walk per day, 5 d·wk-1 (long bout) and the other three 10-min walks per day, also 5 d·wk-1 (short bouts). All walking was at 70–80% of predicted maximal heart rate. Maximal oxygen uptake ([latin capital V with dot above]O2max), body composition, resting arterial blood pressure, fasting plasma lipoprotein variables, and psychological parameters were assessed before and after each program. Results: Overall, subjects completed 88.2 ± 1.1% and 91.3 ± 4.1% of prescribed total walking time in the short- and long-bout programs, respectively. Both programs increased plasma concentrations of high-density lipoprotein cholesterol, and decreased concentrations of triacylglycerol and total cholesterol (all P < 0.05). There were no changes in body mass, but the sum of four skinfolds, waist circumference, and hip circumference were decreased after both walking programs (all P < 0.05). Predicted [latin capital V with dot above]O2max increased with both programs (P < 0.05), but this increase was greater with the program based on short bouts (P < 0.05). Both walking patterns resulted in similar decreases in tension/anxiety (P < 0.05). Conclusion: These findings suggest that three short bouts (10 min) of brisk walking accumulated throughout the day are at least as effective as one continuous bout of equal total duration in reducing cardiovascular risk and improving aspects of mood in previously sedentary individuals.
TL;DR: The need for developing and implementing injury prevention programs targeted toward moderately active adults is suggested, since almost 1/3 of subjects reported permanently stopping their exercise program after injury.
Abstract: Purpose: This study describes the types and frequencies of musculoskeletal injuries among a cohort of adults with above average activity levels who were enrolled in the Aerobics Center Longitudinal Study (Dallas, TX). Methods: Participants were adults aged 20-85 yr who completed a baseline clinical examination (1970-1982) and returned a mailed follow-up survey in 1986. Participants (5,028 men, 1,285 women) were measured for aerobic fitness, height, and body weight during the baseline examination. They reported detailed information about their physical activity levels and injury experiences on the follow-up survey (1986). An injury was defined as any self-reported soft tissue or bone injury that occurred within the previous 12 months. Activity-related injuries were those injuries participants attributed to participation in a formal exercise program. Results: A quarter of all participants reported a musculoskeletal injury. Of these, 83% were activity-related. More than 66% of activity-related injuries occurred in the lower extremity; the knee was listed as the joint most often affected. There were no significant sex differences in the prevalence of injury, regardless of cause. Sport participants had the highest proportion of all-cause and activity-related musculoskeletal injuries among both men and women. Self-perceived severe injuries had a significant negative impact on physical activity levels since almost 1/3 of subjects reported permanently stopping their exercise program after injury. Conclusion: These results suggest the need for developing and implementing injury prevention programs targeted toward moderately active adults. ©2002The American College of Sports Medicine
TL;DR: This study demonstrates that a "McConnell"-based physical therapy treatment regime for PFPS alters the motor control of VMO relative to VL in a functional task and this is associated with a positive clinical outcome.
Abstract: COWAN, S. M., K. L. BENNELL, K. M. CROSSLEY, P. W. HODGES, and J. MCCONNELL. Physical therapy alters recruitment of the vasti in patellofemoral pain syndrome. Med. Sci. Sports Exerc., Vol. 34, No. 12, pp. 1879 –1885, 2002. Purpose: To investigate the effect of physical therapy treatment on the timing of electromyographic (EMG) activity of the vasti in individuals with patellofemoral pain syndrome (PFPS). Methods: Sixty-five (42 female, 23 male) participants aged 40 yr or less (29.2 7.8 yr) diagnosed with PFPS. Participants were randomly allocated into physical therapy treatment (McConnell-based) or placebo groups. Treatment programs were standardized and consisted of six-treatment sessions over 6 wk. Vastus medialis oblique (VMO) and vastus lateralis (VL) EMG activity was recorded with surface electrodes during a stair-stepping task and onsets of EMG activity were measured pre- and post-treatment. Results: Before treatment, the EMG onset of VL occurred before that of VMO in both participant groups. After physical therapy intervention, there was a reduction in symptoms, and this improvement was associated with a significant change in the time of onset of VMO EMG compared with that of VL in both phases of the stair-stepping task. After physical therapy treatment, the onset of VMO preceded VL in the eccentric phase and occurred at the same time in the concentric phase of the stair-stepping task. There was no change in time of EMG onset in the placebo group. Conclusion: This study demonstrates that a “McConnell”-based physical therapy treatment regime for PFPS alters the motor control of VMO relative to VL in a functional task and this is associated with a positive clinical outcome. Key Words: VASTUS MEDIALIS OBLIQUE, ELECTROMYOGRAPHY, STAIR STEPPING, TREATMENT
TL;DR: It is concluded that NEAA are not necessary for stimulation of NB and that there is a dose-dependent effect of EAA ingestion on muscle protein synthesis.
Abstract: This study tests the hypothesis that a dose of 6 g of orally administered essential amino acids (EAAs) stimulates net muscle protein balance in healthy volunteers when consumed 1 and 2 h after resistance exercise. Subjects received a primed constant infusion of L-[(2)H(5)]phenylalanine and L-[1-(13)C]leucine. Samples from femoral artery and vein and biopsies from vastus lateralis were obtained. Arterial EAA concentrations increased severalfold after drinks. Net muscle protein balance (NB) increased proportionally more than arterial AA concentrations in response to drinks, and it returned rapidly to basal values when AA concentrations decreased. Area under the curve for net phenylalanine uptake above basal value was similar for the first hour after each drink (67 +/- 17 vs. 77 +/- 20 mg/leg, respectively). Because the NB response was double the response to two doses of a mixture of 3 g of EAA + 3 g of nonessential AA (NEAA) (14), we conclude that NEAA are not necessary for stimulation of NB and that there is a dose-dependent effect of EAA ingestion on muscle protein synthesis.
TL;DR: The interaction of various established risk factors for acute mountain sickness was examined to examine the influence of susceptibility, preexposure, and ascent rate.
Abstract: SCHNEIDER, M., D. BERNASCH, J. WEYMANN, R. HOLLE, and P. BARTSCH. Acute mountain sickness: influence of susceptibility, preexposure, and ascent rate. Med. Sci. Sports Exerc., Vol. 34, No. 12, pp. 1886–1891, 2002.PurposeWe examined the interaction of various established risk factors for acute
TL;DR: Although evidence for a threshold intensity was not strong, this analysis of training studies supports the use of 45% VO(2R) as a minimal effective training intensity for higher fit subjects and 30%VO( 2R) for lower fit subjects.
Abstract: Purpose: The American College of Sports Medicine has stated that aerobic training needs to occur at a minimum threshold intensity of 50% VO 2max for most healthy adults and at 40% VO 2max for those with a very low initial fitness. Recently, the concept of VO 2 reserve (%VO 2 R. i.e., a percentage of the difference between maximum and resting VO 2 ) has been introduced for prescribing exercise intensity. This analysis was designed to determine the threshold intensity for improving cardiorespiratory fitness expressed as %VO 2 R units. Methods: Previous studies in healthy subjects (N = 18) that evaluated the results of training at low-to-moderate intensities (i.e., ≤60% VO 2max ) were identified. The original studies described the intensity of exercise variously as %VO 2max , %HRR, %HR max , or as a specific HR value. In each case, the intensity was translated into %VO 2 R units. Results: Exercise training intensities below approximately 45% VO 2 R were consistently ineffective at increasing VO 2max in studies that used subjects with mean initial VO 2max values > 40 mL.min -1 .kg -1 . In studies using subjects with mean initial VO 2max values < 40 mL.min 1 .kg -1 , no intensity was found to be ineffective. For this latter group of subjects, the lowest intensities examined were approximately 30% VO 2 R. Conclusion: Although evidence for a threshold intensity was not strong, this analysis of training studies supports the use of 45% VO 2 R as a minimal effective training intensity for higher fit subjects and 30% VO 2 R for lower fit subjects.
TL;DR: The present data confirm prior research, in that repeated supramaximal HIT can significantly improve 40-km time trial performance, and it is shown that when HIT incorporates P(max) as the interval intensity and 60% of T(max).
Abstract: LAURSEN, P. B., C. M. SHING, J. M. PEAKE, J. S. COOMBES, and D. G. JENKINS. Interval training program optimization in highly trained endurance cyclists. Med. Sci. Sports Exerc., Vol. 34, No. 11, pp. 1801–1807, 2002. Purpose: The purpose of this study was to examine the influence of three different high-intensity interval training (HIT) regimens on endurance performance in highly trained endurance athletes. Methods: Before, and after 2 and 4 wk of training, 38 cyclists and triathletes (mean SD; age 25 6 yr; mass 75 7 kg; V u O2peak 64.5 5.2 mL·kg 1 ·min 1 ) performed: 1) a progressive cycle test to measure peak oxygen consumption (V u O2peak) and peak aerobic power output (PPO), 2) a time to exhaustion test (Tmax) at their V u O2peak power output (Pmax), as well as 3) a 40-km time-trial (TT40). Subjects were matched and assigned to one of four training groups (G1, N 8, 8 60% Tmax at Pmax, 1:2 work:recovery ratio; G2, N 9, 8 60% Tmax at Pmax, recovery at 65% HRmax ;G 3, N 10, 12 30 s at 175% PPO, 4.5-min recovery; GCON, N 11). In addition to G1 ,G 2, and G3 performing HIT twice per week, all athletes maintained their regular low-intensity training throughout the experimental period. Results: All HIT groups improved TT40 performance (4.4 to 5.8%) and PPO (3.0 to 6.2%) significantly more than GCON (0.9 to 1.1%; P 0.05). Furthermore, G1 (5.4%) and G2 (8.1%) improved their V u O2peak significantly more than GCON (1.0%; P 0.05). Conclusion: The present study has shown that when HIT incorporates Pmax as the interval intensity and 60% of Tmax as the interval duration, already highly trained cyclists can significantly improve their 40-km time trial performance. Moreover, the present data confirm prior research, in that repeated supramaximal HIT can significantly improve 40-km time trial performance. Key Words: CYCLIST, ENDURANCE PERFORMANCE, OXYGEN UPTAKE, SHORTTERM TRAINING
TL;DR: It was suggested that the neural input used in the fatigued condition did not constitute an optimal solution and may have played a role in decreasing maximal jump height achievement.
Abstract: PURPOSE: The aim of this study was to investigate the segmental coordination of vertical jumps under fatigue of the knee extensor and flexor muscles. METHODS: Eleven healthy and active subjects performed maximal vertical jumps with and without fatigue, which was imposed by requesting the subjects to extend/flex their knees continuously in a weight machine, until they could not lift a load corresponding to approximately 50% of their body weight. Knee extensor and flexor isokinetic peak torques were also measured before and after fatigue. Video, ground reaction forces, and electromyographic data were collected simultaneously and used to provide several variables of the jumps. RESULTS: Fatiguing the knee flexor muscles did not reduce the height of the jumps or induce changes in the kinematic, kinetic, and electromyographic profiles. Knee extensor fatigue caused the subjects to adjust several variables of the movement, in which the peak joint angular velocity, peak joint net moment, and power around the knee were reduced and occurred earlier in comparison with the nonfatigued jumps. The electromyographic data analyses indicated that the countermovement jumps were performed similarly, i.e., a single strategy was used, irrespective of which muscle group (extensor or flexors) or the changes imposed on the muscle force-generating characteristics (fatigue or nonfatigue). The subjects executed the movements as if they scaled a robust template motor program, which guided the movement execution in all jump conditions. It was speculated that training programs designed to improve jump height performance should avoid severe fatigue levels, which may cause the subjects to learn and adopt a nonoptimal and nonspecific coordination solution. CONCLUSION: It was suggested that the neural input used in the fatigued condition did not constitute an optimal solution and may have played a role in decreasing maximal jump height achievement.
TL;DR: The data indicate high-intensity REX training was successful for improving BMD of the femoral neck in healthy elderly subjects and suggest REX increased bone turnover, which over time may lead to further changes in BMD.
Abstract: VINCENT, K. R., and R. W. BRAITH. Resistance exercise and bone turnover in elderly men and women. Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 17–23.PurposeThis investigation examined the effect of 6 months of high- or low-intensity resistance exercise (REX) on bone mineral density (BMD) and b
TL;DR: The APARQ has acceptable to good reliability and acceptable validity, but further validation using other methods and in other population groups is required.
Abstract: BOOTH, M. L., A. D. OKELY, T. CHEY, and A. BAUMAN. The reliability and validity of the Adolescent Physical Activity Recall Questionnaire. Med. Sci. Sports Exerc., Vol. 34, No. 12, pp. 1986–1995, 2002.PurposeThis study assessed the test-retest reliability and validity of the Adolescent Physic
TL;DR: It is concluded that running, a weight bearing exercise, is associated with larger site-specific BMD than swimming or cycling, that the generalized anatomical distribution of loads in triathlon appears not to significantly enhance total body BMD status, and that knee extension strength is only a weak correlate and independent predictor of BMD in adolescent females.
Abstract: DUNCAN, C. S., C. J. R. BLIMKIE, C. T. COWELL, S. T. BURKE, J. N. BRIODY, and R. HOWMAN-GILES. Bone mineral density (BMD) in adolescent female athletes: relationship to exercise type and muscle strength. Med. Sci. Sports Exerc., Vol. 34, No. 2, pp. 286–294, 2002.PurposeThis study investigated the in
TL;DR: The results indicated that to hit the ball with the medial side of the foot, a complicated series of rotational motions are required for the side-foot kick.
Abstract: NUNOME, H, T ASAI, Y IKEGAMI, and S SAKURAI A Three-dimensional kinetic analysis of side-foot and instep soccer kicks Med Sci Sports Exerc, Vol 34, No 12, pp 2028–2036, 2002PurposeThe purpose of this study was to identify the kinetic aspects of side-foot and instep soccer kicks