Foot Cooling between Interval Bouts Enhances Repeated Lower Limb Power Performance: The Role of Delaying Fatigue.

This study aimed to investigate whether interbout foot cooling (FC) may enhance repeated lower limb power performance and the corresponding physiological responses based on interset FC, which has been demonstrated to enhance leg-press performance. In a repeated-measures crossover design, ten active men (aged 21.5 ± 1.5 years, exercising >3 times per week) performed four bouts of 10-s cycle ergometer sprints with interbout FC at 10°C water for 2.5 min or non-cooling (NC) with a 5-day interval. The results indicated that FC elicited higher total work (27.57 ± 5.66 kJ vs. 26.55 ± 5.76 kJ) and arousal scores than NC (p < 0.05). Furthermore, under the NC condition, participants decreased mean power (p < 0.05) with no alteration of vastus lateralis (VL) electromyography (EMG) activities after the second bout; whereas under the FC condition, participants maintained steady mean power accompanied by increased VL EMG activities in the last two bouts (p < 0.05). Jointly, participants had higher mean power ([3rd = 10.14 ± 1.15 vs. 9.37 ± 1.30; 4th = 9.79 ± 1.22 vs. 9.23 ± 1.27] W/kg) and VL EMG activities in the last two bouts under the FC than NC condition (p < 0.05). However, perceived exertion and the heart rate were comparable between the two conditions (p > 0.05). In conclusion, interbout FC elicited a higher arousal level and repeated lower limb power performance, which could be explained by delaying peripheral fatigue via increasing excitatory drive and recruiting additional motor units to compensate for fatigue-related responses and power decrements.

Running interval training combined with blood flow restriction increases maximal running performance and muscular fitness in male runners.

We investigated the effects of 8 weeks (3 days per week) of running interval training (RIT) combined with blood flow restriction (RIT-BFR) on the maximal running performance (RPmax), isokinetic muscle strength, and muscle endurance in athletes. Twenty endurance-trained male runners were pair-matched and randomly assigned to the RIT-BFR and RIT groups. The RIT-BFR group performed RIT (50% heart rate reserve, 5 sets of 3 min each, and 1-min rest interval) with inflatable cuffs (1.3× resting systolic blood pressure), and the RIT group performed the same RIT without inflatable cuffs. RPmax, isokinetic muscle strength, and muscle endurance were assessed at pre-, mid-, and post-training. Compared with the RIT group, the RIT-BFR group exhibited a significantly (p < 0.05) greater increase in RPmax, isokinetic knee extensor and flexor strength, and knee extensor endurance after 24 training sessions. These results suggested that RIT-BFR may be a feasible training strategy for improving muscular fitness and endurance running performance in distance runners.

Running Training Combined With Blood Flow Restriction Increases Cardiopulmonary Function and Muscle Strength in Endurance Athletes.

ABSTRACT: Chen, Y-T, Hsieh, Y-Y, Ho, J-Y, Lin, T-Y, and Lin, J-C. Running training combined with blood flow restriction increases cardiopulmonary function and muscle strength in endurance athletes . J Strength Cond Res 36(5): 1228-1237, 2022-We investigated the effects of 8 weeks (3 d/wk) of running training (RT) combined with blood flow restriction (RT-BFR) on cardiopulmonary function and muscle strength in endurance athletes. Twenty endurance-trained male athletes (19-25 years; 177.6 ± 2.4 cm; 69.0 ± 2.2 kg) were pair matched and randomly assigned to RT-BFR and RT groups. The RT-BFR group performed running sessions (50% heart rate reserve; 3-minute × 5 sets; 1-minute rest interval) with pressure cuffs (1.3 × resting systolic blood pressure), whereas the RT group performed the same running sessions without pressure cuffs. V̇o2max, muscle mass, isokinetic muscle strength, and hormones were assessed at pre-, mid- and posttraining. Compared with the RT group, the RT-BFR group exhibited a significantly greater increase in V̇o2max (5.1 vs. -1.1%) and isokinetic knee extensor strength (16.5 vs. -5.9%). In addition, RT-BFR group presented higher leg muscle mass (10.3 vs. 9.7 kg) than that of RT group after 8 weeks of training. Furthermore, testosterone to cortisol (T:C) ratio at 24 hours after training session at pre-, mid-, and posttraining were maintained in the RT-BFR group, whereas significant decreases of T:C ratio at 24 hours after training session were observed in the RT group. These results suggested that RT combined with BFR may be a practical training strategy for promoting cardiopulmonary function and muscle strength in endurance runners.

Two weeks of detraining reduces cardiopulmonary function and muscular fitness in endurance athletes.

We investigated the effects of 2 weeks of detraining on cardiopulmonary function and muscular fitness in 15 endurance-trained male athletes (age: 19-26 years; height: 176.1 ± 7.5 cm; body mass: 68.3 ± 7.6 kg). VO2max, exercise time to exhaustion (ET), maximal stroke volume (SVmax), maximal heart rate (HRmax), isokinetic muscle strength, and muscle endurance were measured before and after 2 weeks of detraining. We determined that short-term detraining resulted in a significant decrease (p < 0.05) in VO2max, ET, SVmax and isokinetic knee extensor strength but not in isokinetic knee flexor strength or muscle endurance. HRmax and body mass increased significantly (p < 0.05), whereas body fat percentage remained stable after detraining. Furthermore, significant correlations were identified between VO2max and SVmax (p < 0.01, r = 0.6) and between VO2max and knee extensor strength (p < 0.01, r = 0.6). The results suggest that 2 weeks of detraining reduces cardiopulmonary functions, possibly as a result of the attenuation of hemodynamic and neuromuscular adaptations. Moreover, we observed that short periods of detraining appeared to increase lean mass and maintain muscle endurance in endurance runners.HighlightsTwo weeks of detraining reduces VO2max, SVmax and muscle strength but maintains muscle endurance in male runners.Short periods of detraining may enhance anabolic hormonal milieu and increase lean mass.Detraining reduced cardiopulmonary function is associated with attenuation of hemodynamic and muscle adaptations.

Effects of Running Exercise Combined With Blood Flow Restriction on Strength and Sprint Performance.

ABSTRACT: Chen, YT, Hsieh, YY, Ho, JY, and Lin, JC. Effects of running exercise combined with blood flow restriction on strength and sprint performance. J Strength Cond Res 35(11): 3090-3096, 2021-We investigated muscle strength and sprint performance after combining running exercise (RE) with blood flow restriction (BFR). Twelve male sprinters received 2 experimental warm-ups: (a) RE (50% heart rate reserve, 2 minutes × 5 sets, 1-minute rest interval) with BFR (occlusion pressure: 1.3 × resting systolic blood pressure) warm-up, namely RE-BFR; and (b) RE without BFR warm-up, namely RE. Isokinetic strength or 60-m sprint performance was assessed after a 5-minute recovery from each experimental warm-up. All subjects completed 4 exercise trials in a counterbalanced order: (a) RE-BFR-strength; (b) RE-strength; (c) RE-BFR-sprint; and (d) RE-sprint. Muscle activation (during RE), blood lactate (BLa) (pre- and post-REs), heart rate (HR), and rating of perceived exertion (RPE) (pre- and post-REs and at a 5-minute recovery) were determined during each experimental warm-up. The isokinetic knee flexor strength and the hamstring-quadriceps (H:Q) ratio observed for the RE-BFR warm-up were significantly higher than those observed for the RE warm-up (p < 0.05). However, no differences (p > 0.05) in the isokinetic knee extensor strength and 60-m sprint performance were observed between the 2 warm-ups. Running exercise-BFR warm-up induced a higher level of vastus lateralis and biceps femoris muscle activation than did RE warm-up (p < 0.05). Furthermore, RE-BFR warm-up induced higher HR, RPE, and BLa values than did RE warm-up after RE and at a 5-minute recovery (p < 0.05). These results suggest that RE-BFR warm-up may augment physiological responses and improve the H:Q ratio and isokinetic knee flexor strength. Thus, RE-BFR warm-up may be considered a practical warm-up strategy for promoting muscle strength and reducing the risk of hamstring injury in male sprinters.

The subject-dependent, cumulative, and recency association of aerobic fitness with academic performance in Taiwanese junior high school students.

BACKGROUND: The objective of the current study was to examine whether the relation between aerobic fitness and academic achievement during adolescence is subject-dependent, and to investigate cumulative and recency effects. METHODS: This study made use of two nationwide datasets. The first was the aerobic fitness profile of junior high school students collected by the Ministry of Education in Taiwan. The second contained the scores on the Basic Competence Test for Junior High School Students (BCTJH). The sample consisted of 382,259 students who completed the BCTJH in the 5 years between 2009 and 2013. Data on each student's aerobic fitness during their three years of junior high school were matched with their exam results at the end of this period. RESULTS: The results revealed that students classified as highly-fit during at least one of the three years had higher BCTJH scores than those who never achieved this level, with the size of effect increasing with the length of time that fitness was maintained. Additionally, aerobic fitness in the final year was more closely linked to BCTJH scores than that in the earlier two years. Fitness was also more strongly associated with exam performance in math, science and social science, relative to language-related subjects. CONCLUSIONS: Our findings suggest that while aerobic fitness is positively related to academic achievement in Taiwanese junior high school students, the relationship depends on academic subject, as well as the length and time of being aerobically fit.

Effects of acute exposure to mild simulated hypoxia on hormonal responses to low-intensity resistance exercise in untrained men.

This study examined hormonal responses to low-intensity resistance exercise under mild simulated hypoxia. Ten resistance untrained men performed five sets of 15 repetitions of squat exercise at 30% of 1RM under normobaric hypoxia (FiO2 = 15%) and normoxia in a cross-over and counter-balanced design. Blood lactate (LAC), growth hormone (GH), total testosterone (T) and cortisol (C) were measured at pre-exercise, immediately post-exercise and 15 minutes post-exercise. LAC, GH and T significantly increased immediately after squat exercise in both trials (p < 0.05). While T returned to baseline, GH remained significantly greater at 15 minutes post-exercise. Cortisol significantly decreased immediately after and 15 minutes post-exercise in both trials (p < 0.05). No significant differences were observed between two trials in LAC, GH, T and C. It was concluded that low-intensity resistance exercise performed under mild simulated hypoxia does not induce greater anabolic hormonal responses in resistance untrained men.

Effects of resistance exercise on the HPA axis response to psychological stress during short-term smoking abstinence in men.

PURPOSE: The purpose of this study was to examine the effects of resistance exercise on the hypothalamic-pituitary-adrenal axis (HPA) response to mental challenge, withdrawal symptoms, urge to smoke, and cognitive stress during 24-hour smoking abstinence. METHODS: 8 sedentary smokers (mean±SD age: 20.1±1.7y; height: 171.6±10.8cm; body mass: 70.4±12.0kg; smoking history: 2.9±0.8y) completed a 24-hour ad libitum smoking trial (SMO) followed by two 24-hour smoking abstinence trials. During abstinence trials, participants performed six whole body resistance exercises (EX) or a control condition (CON) in the morning, followed by mental challenge tasks in the afternoon. Plasma adrenocorticotropin hormone (ACTH), and salivary and serum cortisol were measured during each visit at rest (REST), and then before (PRE-EX), immediately after (IP-EX), and 30min after exercise (30-EX); and before (PRE-MC), immediately after (IP-MC), and 30min after mental challenge (30-MC). RESULTS: Resistance exercise significantly (p≤0.05) elevated plasma ACTH and serum cortisol at IP-EX during EX compared with SMO and CON trials. Resting ACTH, salivary and serum cortisol concentrations at Pre-MC did not differ between EX and CON trials. The HPA axis response to mental challenge was similar after EX and CON trials. Finally, resistance exercise did not reduce withdrawal symptoms, urge to smoke, or stress. CONCLUSION: Resistance exercise did not substantially alter resting HPA hormones or the HPA response to mental challenge tasks during 24h of smoking abstinence.

Combining normobaric hypoxia with short-term resistance training has no additive beneficial effect on muscular performance and body composition.

The aim of this study was to determine the effects of short-term resistance training combined with systemic hypoxia on muscular performance and body composition. Eighteen resistance-untrained men (21.3 ± 2.0 years, 172.7 ± 5.5 cm, 67.3 ± 9.7 kg) were matched and assigned to 2 experimental groups: performing 6 weeks of squat exercise training under normobaric hypoxia (H, FiO2 = 15%) or normoxia (N). In both groups, subjects performed 3 weekly sessions (a total of 18 sessions) of 3 sets of back squat at 10-repetition maximum with 2 minutes of rest between sets. Dynamic, isometric, and isokinetic leg strength and body composition were measured under normoxia before and after resistance training. Squat 1 repetition maximum (1RM) improved significantly (p ≤ 0.05) after resistance training in both H and N groups (88.9 ± 16.9 to 109.4 ± 17.0 kg and 90.0 ± 12.2 to 105.6 ± 13.3 kg, respectively). However, there were no changes in maximal isometric and isokinetic leg strength, lean body mass, and fat mass after the resistance training in both groups. In addition, no significant differences were observed between H and N groups in squat 1RM, maximal isometric and isokinetic leg strength, and body composition. The major findings of this study suggest that short-term resistance training performed under normobaric hypoxia has no additive beneficial effect on muscular performance and body composition. In practical terms, our data suggest that the use of systemic hypoxia during short-term resistance training is not a viable method to further enhance muscular performance and body composition in previously resistance-untrained men.

Validity of the Myotest® in measuring force and power production in the squat and bench press.

The purpose of this study was to verify the concurrent validity of a bar-mounted Myotest® instrument in measuring the force and power production in the squat and bench press exercises when compared to the gold standard of a computerized linear transducer and force platform system. Fifty-four men (bench press: 39-171 kg; squat: 75-221 kg) and 43 women (bench press: 18-80 kg; squat: 30-115 kg) (age range 18-30 years) performed a 1 repetition maximum (1RM) strength test in bench press and squat exercises. Power testing consisted of the jump squat and the bench throw at 30% of each subject's 1RM. During each measurement, both the Myotest® instrument and the Celesco linear transducer of the directly interfaced BMS system (Ballistic Measurement System [BMS] Innervations Inc, Fitness Technology force plate, Skye, South Australia, Australia) were mounted to the weight bar. A strong, positive correlation (r) between the Myotest and BMS systems and a high correlation of determination (R2) was demonstrated for bench throw force (r = 0.95, p < 0.05) (R2 = 0.92); bench throw power (r = 0.96, p < 0.05) (R2 = 0.93); squat jump force (r = 0.98, p < 0.05) (R2 = 0.97); and squat jump power (r = 0.91, p < 0.05) (R2 = 0.82). In conclusion, when fixed on the bar in the vertical axis, the Myotest is a valid field instrument for measuring force and power in commonly used exercise movements.

Effects of a whole body compression garment on markers of recovery after a heavy resistance workout in men and women.

The primary purpose of this investigation was to evaluate the influence of a whole body compression garment on recovery from a typical heavy resistance training workout in resistance-trained men and women. Eleven men (mean +/- SD: age, 23.0 +/- 2.9 years) and 9 women (mean +/- SD: age 23.1 +/- 2.2 years) who were highly resistance trained gave informed consent to participate in the study. A within-group (each subject acted as their own control), balanced, and randomized treatment design was used. Nutritional intakes, activity, and behavioral patterns (e.g., no pain medications, ice, or long showers over the 24 hours) were replicated 2 days before each test separated by 72 hours. An 8-exercise whole body heavy resistance exercise protocol using barbells (3 sets of 8-10 repetition maximum, 2.0- to 2.5-minute rest) was performed after which the subject showered and put on a specific whole body compression garment one designed for women and one for men (CG) or just wore his/her normal noncompression clothing (CON). Subjects were then tested after 24 hours. Dependent measures included sleep quality, vitality rating, resting fatigue rating, muscle soreness, muscle swelling via ultrasound, reaction movement times, bench throw power, countermovement vertical jump power, and serum concentrations of creatine kinase (CK) measured from a blood sample obtained via venipuncture of an arm vein. We observed significant (p < or = 0.05) differences between CG and CON conditions in both men and women for vitality (CG > CON), resting fatigue ratings (CG < CON), muscle soreness (CG < CON), ultrasound measure swelling (CG < CON), bench press throw (CG > CON), and CK (CG < CON). A whole body compression garment worn during the 24-hour recovery period after an intense heavy resistance training workout enhances various psychological, physiological, and a few performance markers of recovery compared with noncompressive control garment conditions. The use of compression appears to help in the recovery process after an intense heavy resistance training workout in men and women.

l-Carnitine l-tartrate supplementation favorably affects biochemical markers of recovery from physical exertion in middle-aged men and women.

The purpose of this study was to examine the effects of Carnipure tartrate (Lonza, Allendale, NJ) supplementation (total dose of 2 g/d of l-carnitine) on markers of performance and recovery from physical exertion in middle-aged men and women. Normally active and healthy men (n = 9, 45.4 +/- 5.3 years old) and women (n = 9, 51.9 +/- 5.0 years old) volunteered to participate in the investigation. Double-blind, placebo, balanced treatment presentation and crossover design were used with 3 weeks and 3 days of supplementation followed by a 1-week washout period before the other counterbalanced treatment was initiated. After 3 weeks of each supplementation protocol, each participant then performed an acute resistance exercise challenge of 4 sets of 15 repetitions of squat/leg press at 50% 1-repetition maximum and continued supplementation over the recovery period that was evaluated. Blood samples were obtained at preexercise and at 0, 15, 30, and 120 minutes postexercise during the acute resistance exercise challenge and during 4 recovery days as well. Two grams of l-carnitine supplementation had positive effects and significantly (P < or = .05) attenuated biochemical markers of purine metabolism (ie, hypoxanthine, xanthine oxidase), free radical formation (malondialdehyde), muscle tissue disruption (myoglobin, creatine kinase), and muscle soreness after physical exertion. However, markers of physical performance (ie, strength, power, get up and go) were not affected by supplementation. These findings support our previous findings of l-carnitine in younger people that such supplementation can reduce chemical damage to tissues after exercise and optimize the processes of muscle tissue repair and remodeling.

Endocrine response patterns to acute unilateral and bilateral resistance exercise in men.

Rehabilitation programs and research experiments use single-arm protocols in which the contralateral arm is not functional or used as a control limb. This study was interested in determining the hormonal signal impacts of such one- versus two-arm exercise responses that might have an impact on adaptational changes with training. The purpose was to examine the acute hormonal responses to a unilateral and a bilateral upper-body resistance exercise (RE) protocol. A balanced randomized treatment intervention with series time frame for blood collections before and after exercise was used as the basic experimental design. Ten recreationally resistance trained men (18-25 years, 20.4 +/- 1.2 years, 175.6 +/- 4.5 cm, 81.7 +/- 9.3 kg) gave informed consent to participate in the investigation. Each subject performed unilateral (dominant arm only) and bilateral upper-body RE protocol separated by 1 week in a balanced randomized fashion. The RE protocol consisted of 3 sets of 10 repetitions of 5 different dumbbell upper-body exercises at 80% of 1-repetition maximum, and blood samples were obtained before and 5, 15, and 30 minutes immediately postexercise (IP). Blood was obtained and analyzed for lactate, immunoreactive growth hormone (iGH), cortisol (C), total testosterone (T), and insulin concentrations. Total volume of work also was determined for the 2 exercise sessions. Total volume of work performed during the unilateral protocol was 52.1% of that for the bilateral protocol. Both RE protocols elicited a significant (p < or = 0.05) increase in lactate and iGH, but the increase for the bilateral condition was significantly greater. Cortisol decreased significantly during recovery for the unilateral condition. Testosterone was not affected by either protocol. Insulin was significantly increased at IP and 5 minutes postexercise for both conditions.These results indicate that the hormonal responses to dominant-arm unilateral RE is blunted compared to that for bilateral RE. This differential endocrine response is likely a result of the difference in volume between the protocols. It is important to pay attention to the amount of muscle mass utilized in a resistance exercise protocol to optimize endocrine signaling.

Relationship between off-ice testing variables and on-ice speed in women's collegiate synchronized figure skaters: implications for training.

The purpose of the current investigation was to identify any existing relationships between off-ice performance measures and on-ice performance quantified by speed and acceleration. Twenty-seven women (age 19 +/- 1 year; body mass (59.5 +/- 6.8 kg; height 164.6 +/- 6.35 cm; body fat 23.2 +/- 3.9%) who were collegiate synchronized figure skaters volunteered for the investigation. To examine the relationship between off-ice performance and on-ice speed and acceleration, collegiate synchronized skaters were evaluated on various performance tests over a 1-week period. Off-ice tests completed were peak torque for hip abduction and adduction, 40-yard sprint, vertical jump height, 30-second slide board stride count, and a 1-RM (repetition maximum) squat. On-ice tests included a timed single lap sprint, 4.5-minute (duration of long program) lap count, and an approximately 16.5-m (18-yard blue line to blue line) timed acceleration. Significance was set at P < or = 0.05. This study showed 3 primary findings: (a) slide board stride count was the single best predictor for both single lap on-ice speed and acceleration accounting for 53.5% (adjusted R2 value) of the variance in the single lap test and 42.5% (adjusted R2 value) of the variance in acceleration times; (b) vertical jump height test was the second best predictor for both the single lap test and on-ice acceleration accounting for 36.6% and 39.9% (adjusted R2 values) of the variance in times recorded, respectively; and (c) the best combined predictors for the single lap speed test were slide board stride count and 40-yard dash (R2 = 0.675), whereas the best combined predictors for on-ice acceleration were slide board stride count and vertical jump height test (R2 = 0.571). Conditioning for synchronized skaters to enhance performance of on-the-ice speed and acceleration should include slide board training implementation of plyometric and linear speed training while developing and maintaining 1-RM strength to support power capabilities.

Factors affecting flutter kicking speed in women who are competitive and recreational swimmers.

The purpose of this study was to determine the relationships between possible predictive measures of a 50 m front crawl swimming and a 22.86 m flutter kicking speed. Ten women who were National Collegiate Athletic Association Division I collegiate swimmers and 10 women who were recreational swimmers (mean +/- SD = 20.6 +/- 1.6 years; 66.7 +/- 10.3 kg; 166.7 +/- 8.8 cm) volunteered for the study. Anthropometric measures were obtained including height, leg length, lower leg length, and foot length. Ankle flexibility was assessed by measuring ankle plantar flexion and ankle inversion. Lower body power was measured using a vertical jump. Swimming and kicking speed were measured as the time to complete a 50 m front crawl and a 22.86 m flutter kick, respectively. Significant moderate correlations were demonstrated between ankle plantar flexion and flutter kicking speed (r = 0.509); age and 22.86 m kick time (r = 0.608); age and 50 m swim time (r = 0.476); and 50 m swim time and 22.86 m kick time (r = 0.790). No significant correlations were observed between any of the anthropometric measurements or vertical jump power with either kicking or swimming speed. As anecdotally noted by swim coaches over the years, this study provides some actual data showing that ankle flexibility significantly influences flutter kick capability. Surprisingly, vertical jump power and body size were not strong predictors of kicking or swimming speed in this group of subjects. Strength and conditioning coaches, swim coaches, and athletes should evaluate and carefully develop ankle flexibility to positively contribute to kicking capabilities.

Effect of resistance exercise on muscle steroid receptor protein content in strength-trained men and women.

The purpose of this study was to examine the acute effect of resistance exercise (RE) on muscle androgen receptor (AR) and glucocorticoid receptor (GR) protein content. Fifteen resistance-trained men (n=8; 21+/-1 years, 175.3+/-6.7 cm, 90.8+/-11.6 kg) and women (n=7; 24+/-5 years, 164.6+/-6.7 cm, 76.4+/-15.6 kg) completed 6 sets of 10 repetitions of heavy squats. Blood samples were obtained before RE, after 3 and 6 sets of squats, and 5, 15, 30 and 70 min after RE. Muscle biopsies from the vastus lateralis were obtained before RE, and 10 min and 70 min after RE. Blood samples were analyzed for total and free testosterone concentrations and muscle samples were analyzed for AR and GR protein content. Circulating total testosterone increased significantly (p< or =0.05) in men and free testosterone increased in men and women with exercise. AR was significantly reduced at 70 min post-exercise in men and at 10 min post-exercise in women compared to pre-exercise. There were no changes in GR following RE, but GR was significantly higher in women compared to men. These findings support a current paradigm for stabilization followed by a reduction and then a rebound in the acute AR response to RE but demonstrate that gender differences exist in the timeline of the AR response.

Influences of a dietary supplement in combination with an exercise and diet regimen on adipocytokines and adiposity in women who are overweight.

The influence of a proprietary blend of modified cellulose and cetylated fatty acids (Trisynextrade mark, Imagenetix, Inc., San Diego, CA 92127, USA) on adipocytokine and regional body composition responses to a weight loss program was examined. Twenty-two women (Supplement group (S) (n = 11): age = 36.8 +/- 7.2 years; weight = 87.1 +/- 6.2 kg; % body fat = 43.4 +/- 4.1; Placebo group (P) (n = 11): age = 38.3 +/- 6.8 years; weight = 86.9 +/- 4.7 kg; % body fat = 44.3 +/- 2.0) completed an 8-week placebo-controlled, double-blind study consisting of a caloric restricted diet and cardiovascular exercise. Body composition and serum insulin, leptin, and adiponectin were assessed at pre-, mid-, and post-intervention. From pre- to post-intervention, significant decreases (P < 0.05) were observed for body weight (S: 87.1 +/- 6.2-77.9 +/- 5.1 kg; P: 86.9 +/- 4.7-82.7 +/- 3.8 kg) (P < 0.05 S vs. P), % body fat (S: 43.4 +/- 4.1-36.1 +/- 3.6; P: 44.3 +/- 2.0-40.6 +/- 1.2) (P < 0.05 S vs. P), leptin (S: 28.3 +/- 3.5-16.2 +/- 2.6 ng ml(-1); P: 29.4 +/- 3.2-19.9 +/- 1.1 ng ml(-1)) (P < 0.05 S vs. P), and insulin (S: 7.3 +/- 0.8-5.1 +/- 0.2 mU l(-1); P: 7.7 +/- 0.9-5.1 +/- 0.3 mU l(-1)). Serum adiponectin increased (P < 0.05) (S: 12.2 +/- 2.4-26.3 +/- 3.0 microg ml(-1): 12.6 +/- 2.0-21.8 +/- 3.1 microg ml(-1)) (P < 0.05 for S vs. P). Supplementation with a proprietary blend of modified cellulose and cetylated fatty acids during an 8-week weight loss program exhibited favorable effects on adipocytokines and regional body composition.

Recovery from a national collegiate athletic association division I football game: muscle damage and hormonal status.

The purpose of this study was to examine markers of skeletal muscle tissue damage and circulating anabolic and catabolic hormones to gain insight into the recovery process from Friday until Monday, when a new practice week begins. Twenty-eight National Collegiate Athletic Association Division I football players gave consent to participate in the investigation in the ninth game of the season. Sixteen players started the game and played the entire game (PL), and 12 others did not play and were on the bench during the game (DNP). Each player had fasted blood samples obtained at the same time of day between 1000 and 1200 hours the day before the game (Friday; T1), 18-20 hours after the game (Sunday; T2), and then 42-44 hours after the game (Monday; T3). Blood samples were analyzed for concentrations of creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin, testosterone, and cortisol. The PL players showed significantly (p T1 and T3), myoglobin (T2 > T1 and T3), and LDH (T2 > T1). In contrast, DNP players showed significant differences in cortisol (T3 < T1 and T2) and testosterone:cortisol (T3 > T1). Few changes were observed in testosterone and cortisol changes, indicating stability of the anabolic/catabolic hormones. In conclusion, these data indicate that participation in a college football game late in the season results in some degree of tissue damage but with minimal hormonal responses, which seem to have stabilized at resting concentrations without predominance of cortisol's catabolic presence. As previously noted in the literature, some type of "contact adaptation" to the season may have occurred with regard to tissue damage responses. However, by the ninth game of a season, players do carry soft tissue damage levels above resting ranges into subsequent games, indicating that recovery should be monitored, with coaches being careful with scheduling scrimmage and full-contact drills. How such data implicate overuse injuries remains unclear, considering that hormonal status in this study was highly stable, with catabolic influences minimized by the high level of athlete conditioning. These data again support that high-level conditioning can stabilize anabolic and catabolic hormonal signals and limit acute soft tissue injury, making cerebral concussion (acute and chronic) and traumatic injury the biggest threats to a student-athlete's health and well-being during an American football game.

Effect of resistance exercise on muscle steroidogenesis.

Circulating testosterone is elevated acutely following resistance exercise (RE) and is an important anabolic hormone for muscle adaptations to resistance training. The purpose of this study was to examine the acute effect of heavy RE on intracrine muscle testosterone production in young resistance-trained men and women. Fifteen young, highly resistance-trained men (n = 8; 21 +/- 1 yr, 175.3 +/- 6.7 cm, 90.8 +/- 11.6 kg) and women (n = 7; 24 +/- 5 yr, 164.6 +/- 6.7 cm, 76.4 +/- 15.6 kg) completed 6 sets of 10 repetitions of Smith machine squats with 80% of their 1-repetition maximum. Before RE and 10 and 70 min after RE, muscle biopsies were obtained from the vastus lateralis. Before RE, after 3 and 6 sets of squats, and 5, 15, 30, and 70 min into recovery from RE, blood samples were obtained using venipuncture from an antecubital vein. Muscle samples were analyzed for testosterone, 17beta-hydroxysteroid dehydrogenase (HSD) type 3, and 3beta-HSD type 1 and 2 content. Blood samples were analyzed for glucose and lactate concentrations. No changes were found for muscle testosterone, 3beta-HSD type 1 and 2, and 17beta-HSD type 3 concentrations. However, a change in protein migration in the Bis-Tris gel was observed for 17beta-HSD type 3 postexercise; this change in migration indicated an approximately 2.8 kDa increase in molecular mass. These findings indicate that species differences in muscle testosterone production may exist between rats and humans. In humans, muscle testosterone concentrations do not appear to be affected by RE. This study expands on the current knowledge obtained from animal studies by examining resting and postexercise concentrations of muscle testosterone and steroidogenic enzymes in humans.

Effects of stretching on upper-body muscular performance.

The purpose of this investigation was to examine the influence of upper-body static stretching and dynamic stretching on upper-body muscular performance. Eleven healthy men, who were National Collegiate Athletic Association Division I track and field athletes (age, 19.6 +/- 1.7 years; body mass, 93.7 +/- 13.8 kg; height, 183.6 +/- 4.6 cm; bench press 1 repetition maximum [1RM], 106.2 +/- 23.0 kg), participated in this study. Over 4 sessions, subjects participated in 4 different stretching protocols (i.e., no stretching, static stretching, dynamic stretching, and combined static and dynamic stretching) in a balanced randomized order followed by 4 tests: 30% of 1 RM bench throw, isometric bench press, overhead medicine ball throw, and lateral medicine ball throw. Depending on the exercise, test peak power (Pmax), peak force (Fmax), peak acceleration (Amax), peak velocity (Vmax), and peak displacement (Dmax) were measured. There were no differences among stretch trials for Pmax, Fmax, Amax, Vmax, or Dmax for the bench throw or for Fmax for the isometric bench press. For the overhead medicine ball throw, there were no differences among stretch trials for Vmax or Dmax. For the lateral medicine ball throw, there was no difference in Vmax among stretch trials; however, Dmax was significantly larger (p