Biomedical subjects

Nicholas A Ratamess

Publications and source records attributed to Nicholas A Ratamess.

36 records · Page 2Linked to original sources

PubMed2004

Changes in muscle hypertrophy in women with periodized resistance training.

PURPOSE: Adaptations of arm and thigh muscle hypertrophy to different long-term periodized resistance training programs and the influence of upper body resistance training were examined. METHODS: Eighty-five untrained women (mean age = 23.1 +/- 3.5 yr) started in one of the following groups: total-body training [TP, N = 18 (3-8 RM training range) and TH, N = 21 (8-12 RM training range)], upper-body training [UP, N = 21 (3-8 RM training range) and UH, N = 19, (8-12 RM training range)], or a control group (CON, N = 6). Training took place on three alternating days per week for 24 wk. Assessments of body composition, muscular performance, and muscle cross-sectional area (CSA) via magnetic resonance imaging (MRI) were determined pretraining (T1), and after 12 (T2) and 24 wk (T3) of training. RESULTS: Arm CSA increased at T2 (approximately 11%) and T3 (approximately 6%) in all training groups and thigh CSA increased at T2 (approximately 3%) and T3 (approximately 4.5%) only in TP and TH. Squat one-repetition maximum (1 RM) increased at T2 (approximately 24%) and T3 (approximately 11.5%) only in TP and TH and all training groups increased 1 RM bench press at T2 (approximately 16.5%) and T3 (approximately 12.4%). Peak power produced during loaded jump squats increased from T1 to T3 only in TP (12%) and TH (7%). Peak power during the ballistic bench press increased at T2 only in TP and increased from T1 to T3 in all training groups. CONCLUSIONS: Training specificity was supported (as sole upper-body training did not influence lower-body musculature) along with the inclusion of heavier loading ranges in a periodized resistance-training program. This may be advantageous in a total conditioning program directed at development of muscle tissue mass in young women.

Adaptation, Physiological↗

PubMed2004

Longitudinal tracking of muscular power changes of NCAA Division I collegiate women gymnasts.

Gymnastics relies upon power as a critical component of sports-specific fitness. The purpose of this study was to monitor long-term training adaptations in the power of National Collegiate Athletics Association Division I women gymnasts. Twenty members of a women's gymnastic team (aged 18-22) were tracked over 3 years with the first year a baseline year of testing. Whole body power for the counter-movement (CMJ) and squat (SJ) vertical jump was obtained via force plate analyses at 2 assessment time points during each year (February and November). Results showed significant (p < or = 0.05) and continued increases in peak power output in the CMJ and SJ at each biannual assessment. Improvements of 46% (+1010 W) for the CMJ and 43% (+900 W) for the SJ were observed at the end of the tracking period. Peak power for the CMJ and SJ were recorded at 3210 W (+/-350 W) and 3000 W (+/-152 W), respectively. Associated improvements in the time to peak power of 36% (-0.239 second) and 38% (-0.151 second) were also found for the CMJ and SJ. There were no significant changes in body mass or total skinfold thickness, however, a shift toward improved fat free mass (i.e., lean muscle mass) was apparent. These data underscore the importance that specificity, and more importantly power development, should play in the conditioning of collegiate women gymnasts' training programs.

Adolescent↗

PubMed2004

Changes in exercise performance and hormonal concentrations over a big ten soccer season in starters and nonstarters.

As a consequence of the physiological demands experienced during a competitive soccer season, the antagonistic relationship between anabolic and catabolic processes can affect performance. Twenty-five male collegiate soccer players were studied throughout a season (11 weeks) to investigate the effects of long-term training and competition. Subjects were grouped as starters (S; n = 11) and nonstarters (NS; n = 14). Measures of physical performance, body composition, and hormonal concentrations (testosterone [T] and cortisol [C]) were assessed preseason (T1) and 5 times throughout the season (T2-T6). Starters and NS participated in 83.06% and 16.95% of total game time, respectively. Nonstarters had a significant increase (+1.6%) in body fat at T6 compared to T1. Isokinetic strength of the knee extensors (1.05 rad.sec(-1)) significantly decreased in both S (-12%) and NS (-10%; p < or = 0.05) at T6. Significant decrements in sprint speed (+4.3%) and vertical jump (-13.8%) were found at T5 in S only. Though within normal ranges (10.4-41.6 nmol.L(-1)), concentrations of T at T1 were low for both groups, but increased significantly by T6. Concentrations of C were elevated in both groups, with concentrations at the high end of the normal range (normal range 138-635 nmol.L(-1)) at T1 and T4 in NS and T4 in S, with both groups remaining elevated at T6. Data indicate that players entering the season with low circulating concentrations of T and elevated levels of C can experience reductions in performance during a season, with performance decrements exacerbated in starters over nonstarters. Soccer players should therefore have a planned program of conditioning that does not result in an acute overtraining phenomenon prior to preseason (e.g., young players trying to get in shape quickly in the 6 to 8 weeks in the summer prior to reporting for preseason camp). The detrimental effects of inappropriate training do not appear to be unloaded during the season and catabolic activities can predominate.

Adult↗

PubMed2004

Effect of a cetylated fatty acid topical cream on functional mobility and quality of life of patients with osteoarthritis.

OBJECTIVE: To examine the effect of a topical cream consisting of cetylated fatty acids on functional performance in patients diagnosed with osteoarthritis (OA) of one or both knees. METHODS: Forty patients diagnosed with knee OA were randomly assigned to one of 2 topical treatment groups: (1) cetylated fatty acid (CFA) (n = 20; age 62.7 +/- 11.7 yrs); or (2) placebo group (n = 20; age 64.6 +/- 10.5 yrs). Patients were tested on 3 occasions: (1) baseline (T1), (2) 30 min after initial treatment (T2), and (3) after 30-day treatment of cream application twice per day (T3). Assessments included knee range of motion (ROM), timed "up-and-go" from a chair and stair climbing, medial step-down test, and the unilateral anterior reach. RESULTS: For stair climbing ability and the up-and-go test, significant decreases in time were observed at T2 and T3 compared to T1 in the CFA group only. These differences were significant between groups. Supine ROM of the knees increased at T2 and T3 in CFA group, whereas no difference was observed in the placebo group. For the medial step-down test, significant improvement was observed at T2 and T3 compared to T1 in CFA group. For the unilateral anterior reach, significant improvement was observed for both legs in CFA group and in only the left leg in the placebo group. However, the improvements observed in CFA group were significantly greater than placebo group for both legs. CONCLUSION: Use of a CFA topical cream is an effective treatment for improving knee ROM, ability to ascend/descend stairs, ability to rise from sitting, walk and sit down, and unilateral balance.

Activities of Daily Living↗

PubMed2003

The effects of creatine supplementation on muscular performance and body composition responses to short-term resistance training overreaching.

To determine the effects of creatine supplementation during short-term resistance training overreaching on performance, body composition, and resting hormone concentrations, 17 men were randomly assigned to supplement with 0.3 g/kg per day of creatine monohydrate (CrM: n=9) or placebo (P: n=8) while performing resistance exercise (5 days/week for 4 weeks) followed by a 2-week taper phase. Maximal squat and bench press and explosive power in the bench press were reduced during the initial weeks of training in P but not CrM. Explosive power in the bench press, body mass, and lean body mass (LBM) in the legs were augmented to a greater extent in CrM ( P<or=0.05) by the end of the 6-week period. A tendency for greater 1-RM squat improvement ( P=0.09) was also observed in CrM. Total testosterone (TT) and the free androgen index (TT/SHBG) decreased in CrM and P, reaching a nadir at week 3, whereas sex hormone binding globulin (SHBG) responded in an opposite direction. Cortisol significantly increased after week 1 in CrM (+29%), and returned to baseline at week 2. Insulin was significantly depressed at week 1 (-24%) and drifted back toward baseline during weeks 2-4. Growth hormone and IGF-I levels were not affected. Therefore, some measures of muscular performance and body composition are enhanced to a greater extent following the rebound phase of short-term resistance training overreaching with creatine supplementation and these changes are not related to changes in circulating hormone concentrations obtained in the resting, postabsorptive state. In addition, creatine supplementation appears to be effective for maintaining muscular performance during the initial phase of high-volume resistance training overreaching that otherwise results in small performance decrements.

Adaptation, Physiological↗

PubMed2003

Increasing fluid milk favorably affects bone mineral density responses to resistance training in adolescent boys.

This study examined the effects of increasing milk on bone and body composition responses to resistance training in adolescents. Twenty-eight boys (13 to 17 years of age) were randomly assigned to consume, in addition to their habitual diet, 3 servings/day of 1% fluid milk (n=14) or juice not fortified with calcium (n=14) while engaged in a 12-week resistance-training program. For all subjects combined, there were significant (P<or=.05) changes in height (+0.5%), sigmaseven skin folds (-7.7%), body mass (+2.6%), lean body mass (+5.1%), fat mass (-9.3%), whole-body bone mineral content (+3.6%), bone mineral density (+1.8%), and maximal strength in the squat (+43%) and bench press (+23%). Compared with juice, the milk group had a significantly greater increase in bone mineral density (0.014 vs 0.028 g/cm(2)). Increasing intake of milk in physically active adolescent boys may enhance bone health.

Absorptiometry, Photon↗

PubMed2003

Physiological changes with periodized resistance training in women tennis players.

PURPOSE: To compare the physiological and performance adaptations between periodized and nonperiodized resistance training in women collegiate tennis athletes. METHODS: Thirty women (19 +/- 1 yr) were assigned to either a periodized resistance training group (P), nonperiodized training group (NV), or a control group (C). Assessments for body composition, anaerobic power, VO2(max), speed, agility, maximal strength, jump height, tennis-service velocity, and resting serum hormonal concentrations were performed before and after 4, 6, and 9 months of resistance training performed 2-3 d.wk (-1). RESULTS: Nine months of resistance training resulted in significant increases in fat-free mass; anaerobic power; grip strength; jump height; one-repetition maximum (1-RM) leg press, bench press, and shoulder press; serve, forehand, and backhand ball velocities; and resting serum insulin-like growth factor-1, testosterone, and cortisol concentrations. Percent body fat and VO2(max) decreased significantly in the P and NV groups after training. During the first 6 months, periodized resistance training elicited significantly greater increases in 1-RM leg press (9 +/- 2 vs 4.5 +/- 2%), bench press (22 +/- 5 vs 11 +/- 8%), and shoulder press (24 +/- 7 vs 18 +/- 6%) than the NV group. The absolute 1-RM leg press and shoulder press values in the P group were greater than the NV group after 9 months. Periodized resistance training also resulted in significantly greater improvements in jump height (50 +/- 9 vs 37 +/- 7%) and serve (29 +/- 5 vs 16 +/- 4%), forehand (22 +/- 3 vs 17 +/- 3%), and backhand ball velocities (36 +/- 4 vs 14 +/- 4%) as compared with nonperiodized training after 9 months. CONCLUSIONS: These data demonstrated that periodization of resistance training over 9 months was superior for enhancing strength and motor performance in collegiate women tennis players.

Adult↗

PubMed2003

The effects of amino acid supplementation on muscular performance during resistance training overreaching.

The purpose of this study was to examine the effects of amino acid supplementation on muscular strength, power, and high-intensity endurance during short-term resistance training overreaching. Seventeen resistance-trained men were randomly assigned to either an amino acid (AA) or placebo (P) group and underwent 4 weeks of total-body resistance training consisting of two 2-week phases of overreaching (phase 1: 3 x 8-12 repetitions maximum [RM], 8 exercises; phase 2: 5 x 3-5 RM, 5 exercises). Muscle strength, power, and high-intensity endurance were determined before (T1) and at the end of each training week (T2-T5). One repetition maximum squat and bench press decreased at T2 in P (5.2 and 3.4 kg, respectively) but not in AA, and significant increases in 1 RM squat and bench press were observed at T3-T5 in both groups. A decrease in the ballistic bench press peak power was observed at T3 in P but not AA. The fatigue index during the 20-repetition jump squat assessment did not change in the P group at T3 and T5 (fatigue index = 18.6 and 18.3%, respectively) whereas a trend for reduction was observed in the AA group (p = 0.06) at T3 (12.8%) but not T5 (15.2%; p = 0.12). These results indicate that the initial impact of high-volume resistance training overreaching reduces muscle strength and power, and it appears that these reductions are attenuated with amino acid supplementation. In addition, an initial high-volume, moderate-intensity phase of overreaching followed by a higher intensity, moderate-volume phase appears to be very effective for enhancing muscle strength in resistance-trained men.

Adolescent↗

PubMed2003

The effects of L-carnitine L-tartrate supplementation on hormonal responses to resistance exercise and recovery.

The purpose of this investigation was to examine the influence of L-carnitine L-tartrate (LCLT) supplementation using a balanced, cross-over, placebo-controlled research design on the anabolic hormone response (i.e., testosterone [T], insulin-like growth factor-I, insulin-like growth factor-binding protein-3 [IGFBP-3], and immunofunctional and immunoreactive growth hormone [GHif and GHir]) to acute resistance exercise. Ten healthy, recreationally weight-trained men (mean +/- SD age 23.7 +/- 2.3 years, weight 78.7 +/- 8.5 kg, and height 179.2 +/- 4.6 cm) volunteered and were matched, and after 3 weeks of supplementation (2 g LCLT per day), fasting morning blood samples were obtained on six consecutive days (D1-D6). Subjects performed a squat protocol (5 sets of 15-20 repetitions) on D2. During the squat protocol, blood samples were obtained before exercise and 0, 15, 30, 120, and 180 minutes postexercise. After a 1-week washout period, subjects consumed the other supplement for a 3-week period, and the same experimental protocol was repeated using the exact same procedures. Expected exercise-induced increases in all of the hormones were observed for GHir, GHif, IGFBP-3, and T. Over the recovery period, LCLT reduced the amount of exercise-induced muscle tissue damage, which was assessed via magnetic resonance imaging scans of the thigh. LCLT supplementation significantly (p < 0.05) increased IGFBP-3 concentrations prior to and at 30, 120, and 180 minutes after acute exercise. No other direct effects of LCLT supplementation were observed on the absolute concentrations of the hormones examined, but with more undamaged tissue, a greater number of intact receptors would be available for hormonal interactions. These data support the use of LCLT as a recovery supplement for hypoxic exercise and lend further insights into the hormonal mechanisms that may help to mediate quicker recovery.

Administration, Oral↗

PubMed2003

Physiological and functional effects of acute low-frequency hand-arm vibration.

The effects of low frequency of vibration have not been widely studied in the scientific literature, yet humans are exposed to such environmental stress everyday. The purpose of this investigation was to examine the physiological responses to low-frequency upper-body limb vibration. Fourteen healthy men were exposed to 1 hour of bilateral hand-arm vibration and control (no vibration) conditions in a counter-balanced, cross-over design separated by 2 days. Subjects gripped handles that were coupled to a vibrating device, which oscillated in an anterior to posterior direction at a constant frequency of 7.5 Hz and a displacement of 0.38 cm. A series of tests were performed prior to and following the vibration to assess cardiovascular response, visual acuity, tremor of the hand and fingers, grip strength, anticipation response, limb girths, and a movement repositioning task. There were significantly (p < or = 0.05) more visual errors postvibration compared with postcontrol on a standardized vision chart. Tremor was significantly reduced during the vibration compared with the control condition. There were no significant changes in grip strength. Mean anticipation response time was significantly increased during the control condition (+3.3%) but not after vibration (+1.0%). There was a significant improvement in the movement repositioning task after vibration compared with control. Heart rates during the vibration protocol were not significantly higher than the control condition. No significant increases in limb size representative of swelling were observed. These data indicate that exposure to 1 hour of low-frequency hand-arm vibration has only minor effects on physiological function.

Adult↗

PubMed2002

Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones.

Thirty-two untrained men [mean (SD) age 22.5 (5.8) years, height 178.3 (7.2) cm, body mass 77.8 (11.9) kg] participated in an 8-week progressive resistance-training program to investigate the "strength-endurance continuum". Subjects were divided into four groups: a low repetition group (Low Rep, n = 9) performing 3-5 repetitions maximum (RM) for four sets of each exercise with 3 min rest between sets and exercises, an intermediate repetition group (Int Rep, n = 11) performing 9-11 RM for three sets with 2 min rest, a high repetition group (High Rep, n = 7) performing 20-28 RM for two sets with 1 min rest, and a non-exercising control group (Con, n = 5). Three exercises (leg press, squat, and knee extension) were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. Maximal strength [one repetition maximum, 1RM), local muscular endurance (maximal number of repetitions performed with 60% of 1RM), and various cardiorespiratory parameters (e.g., maximum oxygen consumption, pulmonary ventilation, maximal aerobic power, time to exhaustion) were assessed at the beginning and end of the study. In addition, pre- and post-training muscle biopsy samples were analyzed for fiber-type composition, cross-sectional area, myosin heavy chain (MHC) content, and capillarization. Maximal strength improved significantly more for the Low Rep group compared to the other training groups, and the maximal number of repetitions at 60% 1RM improved the most for the High Rep group. In addition, maximal aerobic power and time to exhaustion significantly increased at the end of the study for only the High Rep group. All three major fiber types (types I, IIA, and IIB) hypertrophied for the Low Rep and Int Rep groups, whereas no significant increases were demonstrated for either the High Rep or Con groups. However, the percentage of type IIB fibers decreased, with a concomitant increase in IIAB fibers for all three resistance-trained groups. These fiber-type conversions were supported by a significant decrease in MHCIIb accompanied by a significant increase in MHCIIa. No significant changes in fiber-type composition were found in the control samples. Although all three training regimens resulted in similar fiber-type transformations (IIB to IIA), the low to intermediate repetition resistance-training programs induced a greater hypertrophic effect compared to the high repetition regimen. The High Rep group, however, appeared better adapted for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion. Thus, low and intermediate RM training appears to induce similar muscular adaptations, at least after short-term training in previously untrained subjects. Overall, however, these data demonstrate that both physical performance and the associated physiological adaptations are linked to the intensity and number of repetitions performed, and thus lend support to the "strength-endurance continuum".

Adaptation, Physiological↗

PubMed2002

American College of Sports Medicine position stand. Progression models in resistance training for healthy adults.

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.

Adaptation, Physiological↗

PubMed2002

Performance, biochemical, and endocrine changes during a competitive football game.

PURPOSE: This study represents the first time that anaerobic power performance was examined during an actual intercollegiate American football game. In addition, biochemical and endocrine responses also were examined to assess the physiological stress imposed by this competitive contest. METHODS: Twenty-one members of a NCAA Division III football team were divided into two groups. Group one (ST) were starters (N = 11). The second group (RS) consisted of red-shirt players (N = 10). Blood samples were obtained 24 h (Pre1) and 2.5 h (Pre2) before the game and within 15 min of game conclusion (IP). Anaerobic power measures were recorded approximately 10 min before kickoff (pre) and following the first (Q1), second (Q2), third (Q3), and fourth (Q4) quarters. RESULTS: Peak force (PF) and power (PP) in both squat and countermovement jumps decreased (P < 0.05) from pre to Q2 in both ST and RS; however, all variables returned to baseline levels by Q4. When averaged across trials, PF and PP in both jumps were greater (P < 0.05) in ST than RS. No significant changes in testosterone concentrations with respect to time or between groups were seen. Cortisol concentrations were significantly higher for ST at IP than RS. No significant changes in creatine kinase, alanine aminotransferase, urea, or uric acid were observed in either group from Pre2 to IP. In addition, no between group differences were seen in these variables. Myoglobin and aspartate aminotransferase significantly increased from Pre2 to IP in ST, and a significant difference in myoglobin concentrations was seen between the groups at IP. CONCLUSIONS: Performance, biochemical, and endocrine changes in these NCAA Division III football players reflected the stress and muscle damage that occurs as a result of a competitive American football game.

Adult↗

PubMed2002

L-Carnitine L-tartrate supplementation favorably affects markers of recovery from exercise stress.

We examined the influence of L-carnitine L-tartrate (LCLT) on markers of purine catabolism, free radical formation, and muscle tissue disruption after squat exercise. With the use of a balanced, crossover design (1 wk washout), 10 resistance-trained men consumed a placebo or LCLT supplement (2 g L-carnitine/day) for 3 wk before obtaining blood samples on six consecutive days (D1 to D6). Blood was also sampled before and after a squat protocol (5 sets, 15-20 repetitions) on D2. Muscle tissue disruption at the midthigh was assessed using magnetic resonance imaging (MRI) before exercise and on D3 and D6. Exercise-induced increases in plasma markers of purine catabolism (hypoxanthine, xanthine oxidase, and serum uric acid) and circulating cytosolic proteins (myoglobin, fatty acid-binding protein, and creatine kinase) were significantly (P < or = 0.05) attenuated by LCLT. Exercise-induced increases in plasma malondialdehyde returned to resting values sooner during LCLT compared with placebo. The amount of muscle disruption from MRI scans during LCLT was 41-45% of the placebo area. These data indicate that LCLT supplementation is effective in assisting recovery from high-repetition squat exercise.

Adult↗

PubMed2002

Resistance training for health and performance.

Resistance training is recommended by national health organizations for incorporation into a comprehensive fitness program that includes aerobic and flexibility exercise. Its potential benefits on health and performance are numerous; it has been shown to reduce body fat, increase basal metabolic rate, decrease blood pressure and the cardiovascular demands to exercise, improve blood lipid profiles, glucose tolerance, and insulin sensitivity, increase muscle and connective tissue cross-sectional area, improve functional capacity, and relieve low back pain. Many improvements in physical function and athletic performance are associated with the increases in muscle strength, power, endurance, and hypertrophy observed during resistance training. The key element to effective resistance training is supervision by a qualified professional and the proper prescription of the program variables. Proper program design, ie, that which uses progressive overload, variation, and specificity, is essential to maximize the benefits associated with resistance training.

Exercise↗

PubMed2002

The effects of a 10-kilometer run on muscle strength and power.

Recovery of maximal force and power following a 10-km race has not been widely studied in the scientific literature. Ten healthy men who were experienced distance runners participated in this investigation. Data were collected prerace, immediate postrace, and 48 hours postrace to examine the effect of a 10-km race on muscle force production in the lower body. Maximal peak torque was measured via an isokinetic dynamometer at 30 degrees, 180 degrees, and 300 degrees.s-1. A significant (p <or= 0.05) reduction in peak torque for knee flexion was observed at 30 degrees.s-1 immediately postrace. Average power of the knee flexors were significantly decreased immediately postrace. Total work (J) flexion performed over the last 17 repetitions of the 50-repetition test were significantly reduced from baseline values during both the immediate and 48-hour postrace tests. Significant reductions in peak vertical jump force remained reduced 48 hours postrace testing. No changes were observed for jump power after the race. These data indicate that only the hamstring muscle group was not fully recovered to perform the 50-repetition test and that force production in the vertical jump test was compromised 48 hours after a 10-km race. Nevertheless, it appears that strength and power capabilities of the 10-km runner are for the most part restored 48 hours after an all-out 10-km race effort. From a practical perspective, it appears that a minimum of 48 hours should be utilized between multiple trials in 10-km races at track and field meets.

Adolescent↗

PubMed2002

Detraining produces minimal changes in physical performance and hormonal variables in recreationally strength-trained men.

The object of this study was to examine changes in muscular strength, power, and resting hormonal concentrations during 6 weeks of detraining (DTR) in recreationally strength-trained men. Each subject was randomly assigned to either a DTR (n = 9) or resistance training (RT; n = 7) group after being matched for strength, body size, and training experience. Muscular strength and power testing, anthropometry, and blood sampling were performed before the experimental period (T1), after 3 weeks (T2), and after the 6-week experimental period (T3). One-repetition maximum (1RM) shoulder and bench press increased in RT at T3 (p </= 0.05), whereas no significant changes were observed in DTR. Peak power output and mean power output significantly decreased (9 and 10%) in DTR at T2. Peak torque of the elbow flexors at 90 degrees did not change in the RT group but did significantly decrease by 11.9% at T3 compared with T1 in the DTR group. Vertical jump height increased in RT at T2 but did not change in DTR. Neither group displayed any changes in 1RM squat, body mass, percent body fat, or resting concentrations of growth hormone, follicle-stimulating hormone, luteinizing hormone, sex hormone-binding globulin, testosterone, cortisol, or adrenocorticotropin. These data demonstrate that 6 weeks of resistance DTR in recreationally trained men affects power more than it does strength without any accompanying changes in resting hormonal concentrations. For the recreational weight trainer, losses in strength over 6 weeks are less of a concern compared with anaerobic power and upper arm isometric force production. Anaerobic power exercise with a high metabolic component coming from glycolysis might be of importance for reducing the impact of DTR on Wingate power performances. A minimal maintenance training program is recommended for the recreational lifter to offset any reductions in performance.

Adult↗

PubMedDate not supplied

Recreational sports participation is associated with enhanced physical fitness in children.

The purpose of this study was to examine the association between seasonal participation in recreational sports and its influence on physical fitness measures in children. A total of 44 children (20 boys and 24 girls) all in the fifth grade (11.2 +/- 0.3 yr) were tested for flexibility, upper body strength, upper body power, and lower body power. Activity questionnaires examined seasonal participation rates in recreational sports. Spearman rank correlations showed significant correlations between sport participation rates and performance on selected physical fitness tests (p range between 0.34 and 0.55). Subjects participating in recreational sport programs throughout the year (fall, winter, and spring) performed significantly better in tests of upper body strength, upper body power, and lower body power than subjects who did not participate in any sport or subjects who participated in only one sport. These findings suggest that regular participation in recreational sports throughout the year may be associated with higher levels of muscular strength and anaerobic power in children.

Anaerobic Threshold↗