Showing papers in "European Journal of Applied Physiology in 2009"

Assessment of physical activity: a critical appraisal.

Abstract: Assessment of physical activity in a free-living environment is important for understanding relations between physical activity and health and determining the effectiveness of interventions. Techniques include behavioral observation, questionnaires in the form of diaries, recall questionnaires and interviews, and physiological markers like heart rate, calorimetry, and motion sensors. The doubly labeled water method has become the gold standard for the validation of field methods of assessing physical activity. Then, questionnaires show a low reliability and validity but can be adequately applied as an activity-ranking instrument. The heart rate requires individual calibration to be an effective method to assess physical activity only at group level. The indicated method for the assessment of habitual physical activity in daily life is a doubly labeled water validated accelerometer. Future developments are simultaneous measurement of body acceleration and heart rate for the assessment of physical fitness. A new generation of accelerometers will provide information on body posture and activity recognition to allow objective assessment of subjects' habitual activities, options for a healthy change, and effects of the follow-up of any changes.

The effects of protective clothing on energy consumption during different activities.

Abstract: Protective clothing (PPC) can have negative effects on worker performance. Currently little is known about the metabolic effects of PPC and previous work has been limited to a few garments and simple walking or stepping. This study investigated the effects of a wide range of PPC on energy consumption during different activities. It is hypothesized that wearing PPC would significantly increase metabolic rate, disproportionally to its weight, during walking, stepping and an obstacle course. Measuring a person’s oxygen consumption during work can give an indirect, but accurate estimate of energy expenditure (metabolic rate). Oxygen consumption was measured during the performance of continuous walking and stepping, and an obstacle course in 14 different PPC ensembles. Increases in perceived exertion and in metabolic rate (2.4–20.9%) when wearing a range of PPC garments compared to a control condition were seen, with increases above 10% being significant (P < 0.05). More than half of the increase could not be attributed to ensemble weight.

Acute hormonal and neuromuscular responses to hypertrophy, strength and power type resistance exercise

Abstract: The purpose of the current study was to determine the acute neuroendocrine response to hypertrophy (H), strength (S), and power (P) type resistance exercise (RE) equated for total volume. Ten male subjects completed three RE protocols and a rest day (R) using a randomized cross-over design. The protocols included (1) H: 4 sets of 10 repetitions in the squat at 75% of 1RM (90 s rest periods); (2) S: 11 sets of three repetitions at 90% of 1RM (5 min rest periods); and (3) P: 8 sets of 6 repetitions of jump squats at 0% of 1RM (3 min rest periods). Total testosterone (T), cortisol (C), and sex hormone binding globulin (SHBG) were determined prior to (PRE), immediately post (IP), 60 min post, 24 h post, and 48 h post exercise bout. Peak force, rate of force development, and muscle activity from the vastus medialis (VM) and biceps femoris (BF) were determined during a maximal isometric squat test. A unique pattern of response was observed in T, C, and SHBG for each RE protocol. The percent change in T, C, and SHBG from PRE to IP was significantly (p ≤ 0.05) greater in comparison to the R condition only after the H protocol. The percent of baseline muscle activity of the VM at IP was significantly greater following the H compared to the S protocol. These data indicate that significant acute increases in hormone concentrations are limited to H type protocols independent of the volume of work competed. In addition, it appears the H protocol also elicits a unique pattern of muscle activity as well. RE protocols of varying intensity and rest periods elicit strikingly different acute neuroendocrine responses which indicate a unique physiological stimulus.

Efficiency in cycling: a review

Abstract: We focus on the effect of cadence and work rate on energy expenditure and efficiency in cycling, and present arguments to support the contention that gross efficiency can be considered to be the most relevant expression of efficiency. A linear relationship between work rate and energy expenditure appears to be a rather consistent outcome among the various studies considered in this review, irrespective of subject performance level. This relationship is an example of the Fenn effect, described more than 80 years ago for muscle contraction. About 91% of all variance in energy expenditure can be explained by work rate, with only about 10% being explained by cadence. Gross efficiency is strongly dependent on work rate, mainly because of the diminishing effect of the (zero work-rate) base-line energy expenditure with increasing work rate. The finding that elite athletes have a higher gross efficiency than lower-level performers may largely be explained by this phenomenon. However, no firm conclusions can be drawn about the energetically optimal cadence for cycling because of the multiple factors associated with cadence that affect energy expenditure.

Effects of eccentric strength training on biceps femoris muscle architecture and knee joint range of movement.

Abstract: The aim was to determine whether eccentric strengthening changed the muscle architecture of human biceps femoris and consequently, knee range of motion. Twenty-two subjects were randomly assigned to control and experimental groups. The experimental group completed an eccentric strengthening programme for 8 weeks. Outcome measures included hamstring muscle strength (one repetition maximum), the passive knee extension test (PKE) (knee joint angle at which the onset of passive tension occurs), fascicle length (FL) and pennation angle (PA). One repetition maximum increased by 34% (P < 0.01), the PKE test revealed a 5% increase in joint range of motion (P = 0.01), FL increased by 34% (P = 0.01) and PA did not change (P = 0.38). This is the first report of an increase in FL in the biceps femoris following eccentric resistance training. In addition, the results might imply that this fascicle lengthening could lead to an increase in the range of motion of the knee. Clinical implications for rehabilitation and injury prevention are discussed.

Induction and decay of short-term heat acclimation

Abstract: The purpose of this work was to investigate adaptation and decay from short-term (5-day) heat acclimation (STHA). Ten moderately trained males (mean ± SD age 28 ± 7 years; body mass 74.6 ± 4.4 kg; \( \dot{V}_{{{\text{O}}_{ 2{\text{peak}}} }} \) 4.26 ± 0.37 l min−1) underwent heat acclimation (Acc) for 90-min on 5-days consecutively (Ta = 39.5°C, 60% RH), under controlled hyperthermia (rectal temperature 38.5°C). Participants completed a heat stress test (HST) 1 week before acclimation (Acc), then on the 2nd and 8th day (1 week) following Acc (Ta = 35°C, 60% RH). Seven participants completed HSTs 2 and 3 weeks after Acc. HST consisted of 90-min cycling at 40% peak power output before an incremental performance test. Rectal temperature at rest (37.1 ± 0.4°C) was not lowered by Acc (95% CI −0.3 to 0.2°C), after 90-min exercise (38.6 ± 0.5°C) it reduced 0.3°C (−0.5 to −0.1°C) and remained at this level 1 week later (−0.5 to −0.1°C), but not two (0.1°C −0.4 to 0.5°C; n = 7) or 3 weeks. Similarly, heart rate after 90-min exercise (146 ± 21 b min−1) was reduced (−13: −6 to −20 b min−1) and remained at this level after 1 week (−13: −6 to −20 b min−1) but not two (−9: 6 to −23 b min−1; n = 7) or 3 weeks. Performance (746 s) increased 106 s: 59 to 152 s after Acc and remained higher after one (76 s: 31 to 122) but not two (15 s: −88 to 142 s; n = 7) or 3 weeks. Therefore, STHA (5-day) induced adaptations permitting increased heat loss and this persisted 1 week but not 2 weeks following Acc.

Effect of high intensity intermittent training on heart rate variability in prepubescent children

Abstract: The purpose of this study was to observe the effect of high intermittent exercise training on children's heart rate variability (HRV). Thirty-eight children (age 9.6 +/- 1.2 years) were divided into an intermittent (IT, n = 22) and a control group (CON, n = 16). At baseline and after a 7-week training period, HRV parameters, peak oxygen consumption (VO(2peak)) and maximal aerobic velocity (MAV) were assessed. Training consisted of three 30-min sessions composed by short maximal and supramaximal runs at velocities ranging from 100 up to 190% of MAV. HRV was computed in time and frequency domains. Training resulted in a significant increase in MAV and VO(2peak) in IT (P < 0.05) only without any significant change in HRV parameters for the two groups. Thus, 7 weeks of high intermittent exercise training allows to improve aerobic fitness. However, this modality of training was not sufficient enough to underline a possible effect on the heart rate autonomic regulation in children.

One night of sleep deprivation decreases treadmill endurance performance

Abstract: The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60% $$ \dot{V}{\text{O}}_{2\max } $$ followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (T re), mean skin temperature (T sk), heart rate (HR) and respiratory parameters ( $$ \dot{V}{\text{O}}_{2} $$ , $$ \dot{V}{\text{CO}}_{2} $$ , $$ \dot{V}{\text{E}} $$ , RER pre-load only) were measured. Less distance (P = 0.016, d = 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter T re at rest or thermoregulatory responses during the pre-load including heat storage (0.8°C) and T sk. With the exception of raised $$ \dot{V}{\text{O}}_{2} $$ at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min−1: mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants’ perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.

Body composition, fitness, and metabolic health during strength and endurance training and their combination in middle-aged and older women

Abstract: In this study adaptations in body composition, physical fitness and metabolic health were examined during 21 weeks of endurance and/or strength training in 39- to 64-year-old healthy women. Subjects (n = 62) were randomized into endurance training (E), strength training (S), combined strength and endurance training (SE), or control groups (C). S and E trained 2 and SE 2 + 2 times in a week. Muscle strength and maximal oxygen uptake (VO2max) were measured. Leg extension strength increased 9 ± 8% in S (P < 0.001), 12 ± 8% in SE (P < 0.001) and 3 ± 4% in E (P = 0.036), and isometric bench press 20% only in both S and SE (P < 0.001). VO2max increased 23 ± 18% in E and 16 ± 12% in SE (both P < 0.001). The changes in the total body fat (dual X-ray absorptiometry) did not differ between groups, but significant decreases were observed in E (−5.9%, P = 0.022) and SE (−4.8%, P = 0.005). Lean mass of the legs increased 2.2–2.9% (P = 0.004–0.010) in S, SE and E. There were no differences between the groups in the changes in blood lipids, blood pressure or serum glucose and insulin. Total cholesterol and low-density lipoprotein cholesterol decreased and high-density lipoprotein cholesterol increased in E. Both S and SE showed small decreases in serum fasting insulin. Both endurance and strength training and their combination led to expected training-specific improvements in physical fitness, without interference in fitness or muscle mass development. All training methods led to increases in lean body mass, but decreases in body fat and modest improvements in metabolic risk factors were more evident with aerobic training than strength training.

Accuracy, reliability, linearity of Accutrend and Lactate Pro versus EBIO plus analyzer.

Abstract: The accuracy, reliability and linearity in two hand-portable lactate analyzers, the Accutrend Lactate® (AL) and the Lactate Pro™ (LP) versus the EBIO® plus analyzer (EP) were evaluated. For accuracy, duplicate samples recorded on both the AL and LP revealed an overall average difference versus EP (P < 0.05). The limits of agreement between AL and EP were −0.7 to +1.0, and −1.3 to +1.5 mM between LP and EP. Reliability of AL and LP was assessed at different lactate concentrations; coefficient of variation ranged between 1.8 and 3.3% for AL and between 2.8 and 5.0% for LP. AL and LP had a good reliability for intra-, inter-analyzers, and between test strips (ICC r = 0.999). The linearity was determined versus the EP as reference. The slope coefficient of AL (1.0394) was closer to 1 than that of LP (1.1053). On these bases, AL and LP can be individually considered suitable for the sports research field.

Cytokine and hormone responses to resistance training

Abstract: This study examined the effects of heavy resistance training on physiological acute exercise-induced fatigue (5 x 10 RM leg press) changes after two loading protocols with the same relative intensity (%) (5 x 10 RM(Rel)) and the same absolute load (kg) (5 x 10 RM(Abs)) as in pretraining in men (n = 12). Exercise-induced neuromuscular (maximal strength and muscle power output), acute cytokine and hormonal adaptations (i.e., total and free testosterone, cortisol, growth hormone (GH), insulin-like growth factor-1 (IGF-1), IGF binding protein-3 (IGFBP-3), interleukin-1 receptor antagonist (IL-1ra), IL-1beta, IL-6, and IL-10 and metabolic responses (i.e., blood lactate) were measured before and after exercise. The resistance training induced similar acute responses in serum cortisol concentration but increased responses in anabolic hormones of FT and GH, as well as inflammation-responsive cytokine IL-6 and the anti-inflammatory cytokine IL-10, when the same relative load was used. This response was balanced by a higher release of pro-inflammatory cytokines IL-1beta and cytokine inhibitors (IL-1ra) when both the same relative and absolute load was used after training. This enhanced hormonal and cytokine response to strength exercise at a given relative exercise intensity after strength training occurred with greater accumulated fatigue and metabolic demand (i.e., blood lactate accumulation). The magnitude of metabolic demand or the fatigue experienced during the resistance exercise session influences the hormonal and cytokine response patterns. Similar relative intensities may elicit not only higher exercise-induced fatigue but also an increased acute hormonal and cytokine response during the initial phase of a resistance training period.

Paired changes in electromechanical delay and musculo-tendinous stiffness after endurance or plyometric training

Abstract: When measured in vivo electromechanical delay (EMD) depends mainly on the elastic properties of the muscle-tendon unit. Recent studies have shown changes in stiffness of the triceps surae (TS) following a period of training. To confirm the influence of musculo-tendinous stiffness on EMD, this study investigates paired changes in these two parameters after a training period. Two types of training known to induce opposite changes in stiffness were analysed. EMD and musculo-tendinous stiffness were measured on adult subjects before and after 10 weeks of endurance (n = 21) or plyometric (n = 9) trainings. EMD was defined as the time lag between the TS M-wave latency and the onset of muscle twitch evoked at rest by supramaximal electrical stimulations of the posterior tibial nerve. Quick release tests were used to evaluate the musculo-tendinous stiffness of the ankle plantar flexors. The stiffness index was defined as the slope of the relationship between angular stiffness and external torque values. Endurance training, known to preferentially activate the slow, stiffer muscle fibers, leads to a decrease in EMD and to an increase in stiffness index. Following plyometric training, which specifically recruits fast, more compliant fibers, EMD and the stiffness index exhibited adaptations directionally opposite to those seen with endurance training. When pooling the data for the two subject groups, a correlation was found between changes in EMD and changes in musculo-tendinous stiffness indexes. Thus, changes in EMD values are proposed to indirectly link to changes in musculo-tendinous stiffness for subjects involved in muscle training.

Sports performance: is there evidence that the body clock plays a role?

Abstract: Athletic performance shows a time-of-day effect, possible causes for which are environmental factors (which can be removed in laboratory studies), the sleep-wake cycle and the internal “body clock”. The evidence currently available does not enable the roles of these last two factors to be separated. Even so, results indicate that the body clock probably does play some role in generating rhythms in sports performance, and that to deny this is unduly critical. Protocols to assess the separate roles of the body clock and time awake are then outlined. A serious impediment to experimental work is muscle fatigue, when maximal or sustained muscle exertion is required. Dealing with this problem can involve unacceptably prolonged protocols but alternatives which stress dexterity and eye-hand co-ordination exist, and these are directly relevant to many sports (shooting, for example). The review concludes with suggestions regarding the future value to sports physiology of chronobiological studies.

Anatomical predictors of maximum isometric and concentric knee extensor moment.

Abstract: The most important anatomical determinants of in vivo joint moment magnitude have yet to be defined. Relationships between maximal knee extensor moment and quadriceps muscle volume, anatomical (ACSA) and physiological (PCSA) cross-sectional area, muscle architecture and moment arm (MA) were compared. Nineteen untrained men and women performed maximal isokinetic knee extensions under isometric conditions (90 degrees joint angle) and at 30 degrees and 300 degrees s(-1). Magnetic resonance and ultrasound imaging techniques were used to measure vastus lateralis PCSA and fascicle length (FL), quadriceps ACSA, volume and patellar tendon MA. Muscle volume was the best predictor of extensor moment measured isometrically (R(2) = 0.60) and at 30 degrees s(-1)(R (2) = 0.74). PCSA x FL was the best predictor of moment at 300 degrees s(-1) (R(2) = 0.59). MA was not an important predictor. ACSA was the second best predictor at all three speeds and could be recommended as an ideal measure given its relative ease of measurement.

Effects of aquatic resistance training on health and fitness in postmenopausal women

Abstract: To investigate effects of 24 weeks of resistance training with aquatic resistance devices or elastic bands (EB) on markers of cardiovascular health and physical capacity. Forty-six healthy, sedentary postmenopausal women participated. The groups were aquatic exercise (AE; n = 15), EB (n = 21), and control (n = 10). Venous blood chemistry included cholesterol, triglycerides, glucose, and apolipoprotein B. Physical capacity was assessed by the sit-and-reach, knee push-up, 60-s squat, and abdominal crunch tests. Both AE and EB, respectively, showed a significant (P ≤ 0.05) decrease in body fat (14.56, 11.97%) and diastolic blood pressure (8.03, 5.88%), and a significant increase in fat-free mass (2.88, 1.22%), sit-and-reach (27.94, 44.2%), knee push-ups (84.74, 51.59%), and 60-s squats (65.76, 46.04%). AE also showed a significant increase in abdominal crunches (28.11%). Aquatic resistance training can offer significant physiological benefits in health and performance that are comparable to those obtained from EB in this population.

The influence of cold water immersions on adaptation following a single bout of damaging exercise

Abstract: The aim of this investigation was to elucidate the effects of cold water immersions (CWIs) following damaging exercise on the repeated bout effect (RBE). Sixteen males performed two bouts of drop jump exercise separated by 14–21 days. Participants were equally, but randomly assigned to either a CWI (12-min CWI at 15°C) or control group (12-min seated rest). Treatments were given immediately after the first exercise bout, 24, 48 and 72 h post-exercise. No interventions were given following the second bout. Maximum voluntary contraction (MIVC), soreness (DOMS), creatine kinase (CK), thigh girth and range of motion (ROM) were recorded before and for 96 h following the initial and repeated bouts of damaging exercise. All variables, except ROM, showed a significant time effect (P < 0.01) indicating the presence of muscle damage following the initial bout; there were no differences between the CWI and control groups after the initial bout. Following the repeated bout of exercise there was a significant attenuation in the reduction of MIVC (P = 0.002) and a reduction in DOMS (P < 0.001), which is indicative of the RBE. There were no significant differences between groups following the repeated bout of damaging exercise. These data show that CWI had no effect following damaging exercise and did not inhibit the RBE. Despite CWI being used routinely, its efficacy remains unclear and there is a need to elucidate the benefits of this intervention on recovery and adaptation to provide practitioners with evidence based practice.

Seasonal variations in physical activity and implications for human health

Abstract: This review explores the implications of seasonal changes in physical activity for fitness and human health. Photosensitivity and nutrient shortages mediate animal hibernation via the hypothalamus and changes in leptin and ghrelin concentrations. Opportunities for hunting and crop cultivation determine seasonal activity in under-developed human societies, but in developed societies temperature and rainfall are dominant influences, usually over-riding innate rhythms. Both questionnaire data and objective measurements show that many groups from children to the elderly increase their physical activity from winter to spring or summer. Measurements of maximal oxygen intake and muscle strength commonly show parallel seasonal changes. However, potential effects upon body mass and body fat may be counteracted by changes of food intake; subsistence agriculturists sometimes maintain or increase physical activity at the expense of a decrease in body mass. In developed societies, body fat commonly increases during the winter, with parallel changes in blood lipids, blood pressure and blood coagulability; moreover, these changes are not always fully reversed the following summer. Most developed societies show increased all-cause and cardiac mortalities in the winter. Health consequences of seasonal variations in physical activity including an increased vulnerability to cardiac catastrophe and a year-by-year increase in total body fat seem most likely if the average level of physical activity for the year is low. Public health recommendations should underline the importance of maintaining physical activity during adverse environmental conditions by adapting clothing, modifying behaviour and exploiting any available air-conditioned indoor facilities.

Endurance and neuromuscular changes in world-class level kayakers during a periodized training cycle

Abstract: This study was undertaken to analyze changes in selected cardiovascular and neuromuscular variables in a group of elite kayakers across a 12-week periodized cycle of combined strength and endurance training. Eleven world-class level paddlers underwent a battery of tests and were assessed four times during the training cycle (T0, T1, T2, and T3). On each occasion subjects completed an incremental test to exhaustion on the kayak-ergometer to determine maximal oxygen uptake (VO2max), second ventilatory threshold (VT2), peak blood lactate, paddling speed at VO2max (PSmax) and at VT2 (PSVT2), stroke rate at VO2max and at VT2, heart rate at VO2max and at VT2. One-repetition maximum (1RM) and mean velocity with 45% 1RM load (V 45%) were assessed in the bench press (BP) and prone bench pull (PBP) exercises. Anthropometric measurements (skinfold thicknesses and muscle girths) were also obtained. Training volume and exercise intensity were quantified for each of three training phases (P1, P2, and P3). Significant improvements in VO2max (9.5%), VO2 at VT2 (9.4%), PSmax (6.2%), PSVT2 (4.4%), 1RM in BP (4.2%) and PBP (5.3%), V 45% in BP (14.4%) and PBP (10.0%) were observed from T0 to T3. A 12-week periodized strength and endurance program with special emphasis on prioritizing the sequential development of specific physical fitness components in each training phase (i.e. muscle hypertrophy and VT2 in P1, and maximal strength and aerobic power in P2) seems effective for improving both cardiovascular and neuromuscular markers of highly trained top-level athletes.

Changes in serum cartilage oligomeric matrix protein (COMP), plasma CPK and plasma hs-CRP in relation to running distance in a marathon (42.195 km) and an ultra-marathon (200 km) race.

Abstract: Marathon running is frequently associated with numerous cellular changes, but little information is available on the effects of exercise-mediated prolonged impact-stress on cartilage integrity. This study was undertaken to evaluate muscle and cartilage damage with different running distances. Twenty male marathoners and ultra-marathoners participated in the study. Serum COMP and plasma CPK and hs-CRP were measured as markers of cartilage and muscle damage and inflammation. Serum COMP was increased 1.6-fold at 10 km during a marathon race and declined to the pre-race level after 2 days recovery. In contrast, serum COMP was increased 1.9-fold after a 200-km race and maintained until day 3 of recovery, only returning to the pre-race level on day 6. Plasma CPK was increased at 10 km of the marathon race and up to threefold at the end of the race. This was further increased on day 1, only returning to pre-race level on day 6. Plasma CPK was increased 35-fold at the end of the 200-km race and remained increased until day 5. There was no change in plasma hs-CRP during the marathon race, but this was increased 3.4-fold by day 1, returning to the pre-race level on day 4. Plasma hs-CRP increased 40-fold by the end of the 200-km race and was still increased on day 6 of recovery. Therefore, longer distance running may induce more impact-stress both on muscle and cartilage. Further, the required time for recovery may vary with running distance and the tissue type, e.g. cartilage or skeletal muscle as in this case.

Differences in comfort perception in relation to local and whole body skin wettedness.

Abstract: Relevance of local skin wettedness (w (local)) to general thermal comfort while wearing clothing was investigated in eight males. In the experiments, skin wettedness of the whole body (w (body)) was controlled to be around the thermal comfort limit, while w (local) in different target locations of equal area (anterior and dorsal torso, arms, and thighs) was pushed beyond the comfort limit using special test garments. Subjects walked on a treadmill at 4.5 km h(-1) under 22 degrees C 50% RH. Arms and thighs were thermally in discomfort when their w (local) exceeded 0.32. On the other hand, discomfort in the anterior and dorsal torso was initiated when their w (local) arrived at 0.42 and 0.45. That is, the relation of the local comfort limit with w (local) differed depending upon the location. It was observed; however, that general discomfort was not induced when w (body) remained below 0.36 even if w (local) was higher than its local comfort limit.

Energetics of karate (kata and kumite techniques) in top-level athletes.

Abstract: Breath-by-breath O(2) uptake (VO2, L min(-1)) and blood lactate concentration were measured before, during exercise, and recovery in six kata and six kumite karate Word Champions performing a simulated competition. VO2max, maximal anaerobic alactic, and lactic power were also assessed. The total energy cost (VO2TOT mL kg(-1) above resting) of each simulated competition was calculated and subdivided into aerobic, lactic, and alactic fractions. Results showed that (a) no differences between kata and kumite groups in VO2max, height of vertical jump, and Wingate test were found; (b) VO2TOT were 87.8 +/- 6.6 and 82.3 +/- 12.3 mL kg(-1) in kata male and female with a performance time of 138 +/- 4 and 158 +/- 14 s, respectively; 189.0 +/- 14.6 mL kg(-1) in kumite male and 155.8 +/- 38.4 mL kg(-1) in kumite female with a predetermined performance time of 240 +/- 0 and 180 +/- 0 s, respectively; (c) the metabolic power was significantly higher in kumite than in kata athletes (p < or = 0.05 in both gender); (d) aerobic and anaerobic alactic sources, in percentage of the total, were significantly different between gender and disciplines (p < 0.05), while the lactic source was similar; (e) HR ranged between 174 and 187 b min(-1) during simulated competition. In conclusion, kumite appears to require a much higher metabolic power than kata, being the energy source with the aerobic contribution predominant.

Light-intensity activities are important for estimating physical activity energy expenditure using uniaxial and triaxial accelerometers

Abstract: This study evaluated the validity of the total energy expenditure (TEE) estimated using uniaxial (ACCuni) and triaxial (ACCtri) accelerometers in the elderly Thirty-two healthy elderly (64–87 years) participated in this study TEE was measured using the doubly labeled water (DLW) method (TEEDLW) TEEACCuni (679 ± 108 MJ day−1) was significantly lower than TEEDLW (785 ± 154 MJ day−1) and showed wider limits of agreement (−315 to 112 MJ day−1) with a smaller correlation coefficient (r = 0703) TEEACCtri (788 ± 127 MJ day−1) did not differ from TEEDLW and showed narrower limits of agreement (−164 to 172 MJ day−1) with a larger correlation coefficient (r = 0835, P < 0001) The estimated intensities of light activities were significantly lower with ACCuni Greater mediolateral acceleration was observed during 6-min walk tests The results suggest that ACCtri is a better choice than ACCuni for assessing TEE in the elderly

Changes in heart rate recovery after high-intensity training in well-trained cyclists

Abstract: Heart rate recovery (HRR) after submaximal exercise improves after training. However, it is unknown if this also occurs in already well-trained cyclists. Therefore, 14 well-trained cyclists (VO2max 60.3 ± 7.2 ml kg−1 min−1; relative peak power output 5.2 ± 0.6 W kg−1) participated in a high-intensity training programme (eight sessions in 4 weeks). Before and after high-intensity training, performance was assessed with a peak power output test including respiratory gas analysis (VO2max) and a 40-km time trial. HRR was measured after every high-intensity training session and 40-km time trial. After the training period peak power output, expressed as W kg−1, improved by 4.7% (P = 0.000010) and 40-km time trial improved by 2.2% (P = 0.000007), whereas there was no change in VO2max (P = 0.066571). Both HRR after the high intensity training sessions (7 ± 6 beats; P = 0.001302) and HRR after the 40-km time trials (6 ± 3 beats; P = 0.023101) improved significantly after the training period. Good relationships were found between improvements in HRR40-km and improvements in peak power output (r = 0.73; P < 0.0001) and 40-km time trial time (r = 0.96; P < 0.0001). In conclusion, HRR is a sensitive marker which tracks changes in training status in already well-trained cyclists and has the potential to have an important role in monitoring and prescribing training.

Neural adaptations underlying cross-education after unilateral strength training

Abstract: The purpose of this study was to investigate the effects of 4-week (16 sessions) unilateral, maximal isometric strength training on contralateral neural adaptations. Subjects were randomised to a strength training group (TG, n = 15) or to a control group (CG, n = 11). Both legs of both groups were tested for plantar flexion maximum voluntary isometric contractions (MVCs), surface electromyogram (EMG), H-reflexes and V-waves in the soleus (SOL) and gastrocnemius medialis (GM) superimposed during MVC and normalised by the M-wave (EMG/M(SUP), H(SUP)/M(SUP), V/M(SUP), respectively), before and after the training period. For the untrained leg, the TG increased compared to the CG for MVC torque (33%, P < 0.01), SOL EMG/M(SUP) (32%, P < 0.05) and SOL V/M(SUP) (24%, P < 0.05). For the trained leg, the TG increased compared to the CG for MVC torque (40%, P < 0.01), EMG/M(SUP) (SOL: 38%, P < 0.05; GM: 60%, P < 0.05) and SOL V/M(SUP) (72%, P < 0.01). H(SUP)/M(SUP) remained unchanged for both limbs. No changes occurred in the CG. These results reinforce the concept that enhanced neural drive to the contralateral agonist muscles contributes to cross-education of strength.

Resistance exercise-induced changes of inflammatory gene expression within human skeletal muscle.

Abstract: Aberrant local inflammatory signaling within skeletal muscle is now considered a contributing factor to the development of sarcopenia. Recent evidence indicates that chronic resistance training contributes to the control of locally derived inflammation via adaptations to repeated, acute increases in pro-inflammatory mRNA within muscle. However, only a limited number of gene transcripts related to the inflammatory process have been examined in the literature. The present study utilized an acute bout to examine the effects of resistance exercise on several inflammatory-related genes in 24 physically active, post-menopausal women not currently undergoing hormone replacement therapy. Following a standard warm-up, participants completed a lower-body resistance exercise bout consisting of 3 sets of 10 repetitions on machine squat, leg press, and leg extension exercises (80% intensity). Muscle biopsies were obtained from the vastus lateralis of the dominant leg at baseline and 3 h following exercise. Significant (p < 0.05) up-regulation in mRNA content was observed for TNFα, IL1β, IL6, IL8, SOCS2, COX2, SAA1, SAA2, IKKB, cfos, and junB. Muscle mRNA content was not significantly altered at the 0.05 level for IL2, IL5, IL10, or IL12 (p35). Venous blood samples were also obtained at baseline as well as at 3, 24, and 48 h post-exercise. Serum was analyzed for circulating TNFα, IL1β, IL6, IL8, COX2, and SAA with no significant changes observed. These results indicate that resistance exercise is capable of up-regulating transcription of numerous inflammatory mediators within skeletal muscle, and these appear to be worthy of future examination in chronic studies.

The effect of 4 weeks β-alanine supplementation and isokinetic training on carnosine concentrations in type I and II human skeletal muscle fibres

Abstract: Seven male students were supplemented with β-alanine (β-ALG) for 4 weeks (6.4 g day−1) and seven with a matching placebo (PLG). Subjects undertook 4 weeks of isokinetic training with the right leg (T) whilst the left leg was untrained (UT), serving as a control. Each training session consisted of 10 × 10 maximal 90° extension and flexion contractions at 180°/s using a Kin-Com isokinetic dynamometer, with 1 min rest between bouts. Muscle biopsies were taken from the vastus lateralis immediately before and at the end of the supplementation period. Following freeze drying muscle fibres were dissected and characterised by their MHC profile, as type I, IIa, IIx, or as hybrids of these. Carnosine was measured by HPLC. There was a significant increase in carnosine in both T and UT legs of the β-ALG (9.63 ± 3.92 mmol kg−1 dry muscle and 6.55 ± 2.36 mmol kg−1 dry muscle respectively). There was a significant increase in the carnosine content of all fibre phentotypes, with no significant difference between types. There were no significant differences in the changes in muscle or in fibres between the T and UT legs. In contrast there was no significant change in the carnosine content in either the T or UT legs with placebo. The results indicate that 4 weeks training has no effect on the muscle carnosine content. Whilst an increase was seen with β-alanine supplementation, this was not further influenced by training. These findings suggest that β-alanine availability is the main factor regulating muscle carnosine synthesis.

In vivo specific tension of the human quadriceps femoris muscle

Abstract: It is not known to what extent the inter-individual variation in human muscle strength is explicable by differences in specific tension. To investigate this, a comprehensive approach was used to determine in vivo specific tension of the quadriceps femoris (QF) muscle (Method 1). Since this is a protracted technique, a simpler procedure was also developed to accurately estimate QF specific tension (Method 2). Method 1 comprised calculating patellar tendon force (F (t)) in 27 young, untrained males, by correcting maximum voluntary contraction (MVC) for antagonist co-activation, voluntary activation and moment arm length. For each component muscle, the physiological cross-sectional area (PCSA) was calculated as volume divided by fascicle length during MVC. Dividing F (t) by the sum of the four PCSAs (each multiplied by the cosine of its pennation angle during MVC) provided QF specific tension. Method 2 was a simplification of Method 1, where QF specific tension was estimated from a single anatomical CSA and vastus lateralis muscle geometry. Using Method 1, the variability in MVC (18%) and specific tension (16%) was similar. Specific tension from Method 1 (30 +/- 5 N cm(-2)) was similar to and correlated with that of Method 2 (29 +/- 5 N cm(-2); R (2) = 0.67; P < 0.05). In conclusion, most of the inter-individual variability in MVC torque remains largely unexplained. Furthermore, a simple method of estimating QF specific tension provided similar values to the comprehensive approach, thereby enabling accurate estimations of QF specific tension where time and resources are limited.

Different response to eccentric and concentric training in older men and women.

Abstract: Sarcopenia is the age-related loss of muscle mass and strength and has been associated with an increased risk of falling and the development of metabolic diseases. Various training protocols, nutritional and hormonal interventions have been proposed to prevent sarcopenia. This study explores the potential of continuous eccentric exercise to retard age-related loss of muscle mass and function. Elderly men and women (80.6 ± 3.5 years) were randomized to one of three training interventions demanding a training effort of two sessions weekly for 12 weeks: cognitive training (CT; n = 16), conventional resistance training (RET; n = 23) and eccentric ergometer training (EET; n = 23). Subjects were tested for functional parameters and body composition. Biopsies were collected from M.vastus lateralis before and after the intervention for the assessment of fiber size and composition. Maximal isometric leg extension strength (MEL: +8.4 ± 1.7%) and eccentric muscle coordination (COORD: −43 ± 4%) were significantly improved with EET but not with RET (MEL: +2.3 ± 2.0%; COORD: −13 ± 3%) and CT (MEL: −2.3 ± 2.5%; COORD: −12 ± 5%), respectively. We observed a loss of body fat (−5.0 ± 1.1%) and thigh fat (−6.9 ± 1.5%) in EET subjects only. Relative thigh lean mass increased with EET (+2.5 ± 0.6%) and RET (+2.0 ± 0.3%) and correlated negatively with type IIX/type II muscle fiber ratios. It was concluded that both RET and EET are beneficial for the elderly with regard to muscle functional and structural improvements but differ in their spectrum of effects. A training frequency of only two sessions per week seems to be the lower limit for a training stimulus to reveal measurable benefits.

Mechano-transduction to muscle protein synthesis is modulated by FAK.

Abstract: We examined the involvement of focal adhesion kinase (FAK) in mechano-regulated signalling to protein synthesis by combining muscle-targeted transgenesis with a physiological model for un- and reloading of hindlimbs. Transfections of mouse tibialis anterior muscle with a FAK expression construct increased FAK protein 1.6-fold versus empty transfection in the contralateral leg and elevated FAK concentration at the sarcolemma. Altered activation status of phosphotransfer enzymes and downstream translation factors showed that FAK overexpression was functionally important. FAK auto-phosphorylation on Y397 was enhanced between 1 and 6 h of reloading and preceded the activation of p70S6K after 24 h of reloading. Akt and translation initiation factors 4E-BP1 and 2A, which reside up- or downstream of p70S6K, respectively, showed no FAK-modulated regulation. The findings identify FAK as an upstream element of the mechano-sensory pathway of p70S6K activation whose Akt-independent regulation intervenes in control of muscle mass by mechanical stimuli in humans.

Differences in physical fitness among indoor and outdoor elite male soccer players

Abstract: This study compared anthropometric (body height, body mass, percent body fat, fat-free body mass) and physical fitness characteristics (vertical jump height, power-load curve of the leg, 5 and 15 m sprint running time and blood lactate concentrations ([La]b) at submaximal running velocities) among 15 elite male indoor soccer (IS) and 25 elite male outdoor soccer (OS) players. IS players had similar values in body height, body mass, fat-free body mass and endurance running than OS players. However, the IS group showed higher (P < 0.05–0.01) values in percent body fat (28%) and sprint running time (2%) but lower values in vertical jump (15%) and half-squat power (20%) than the OS group. Significant negative correlations (P < 0.05–0.01) were observed between maximal sprint running time, power production during half-squat actions, as well as [La]b at submaximal running velocities. Percent body fat correlated positively with maximal sprint time and [La]b, but correlated negatively with vertical jump height. The present results show that compared to elite OS players, elite IS players present clearly lower physical fitness (lower maximal leg extension power production) characteristics associated with higher values of percent body fat. This should give IS players a disadvantage during soccer game actions.