***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The purpose of this study was to examine the effects of ami-no acid supplementation on muscular strength , power , and high-intensity endurance during short-term resistance training overreaching . Seventeen resistance-trained men were r and omly 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 3–5RM , 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 1RM 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 Abstract Introduction Studies utilizing beta-hydroxy-beta-methylbutyrate ( HMB ) supplementation in trained population s are limited . No long-term studies utilizing HMB free acid ( HMB-FA ) have been conducted . Therefore , we investigated the effects of 12 weeks of HMB-FA supplementation on skeletal muscle hypertrophy , body composition , strength , and power in trained individuals . We also determined the effects of HMB-FA on muscle damage and performance during an overreaching cycle . Methods A three-phase double-blind , placebo- and diet-controlled r and omized intervention study was conducted . Phase 1 was an 8-week-periodized resistance-training program ; Phase 2 was a 2-week overreaching cycle ; and Phase 3 was a 2-week taper . Muscle mass , strength , and power were examined at weeks 0 , 4 , 8 , and 12 to assess the chronic effects of HMB-FA ; and assessment of these , as well as cortisol , testosterone , and creatine kinase ( CK ) was performed at weeks 9 and 10 of the overreaching cycle . Results HMB-FA result ed in increased total strength ( bench press , squat , and deadlift combined ) over the 12-week training ( 77.1 ± 18.4 vs. 25.3 ± 22.0 kg , p < 0.001 ) ; a greater increase in vertical jump power ( 991 ± 168 vs. 630 ± 167 W , p < 0.001 ) ; and increased lean body mass gain ( 7.4 ± 4.2 vs. 2.1 ± 6.1 kg , p < 0.001 ) in HMB-FA- and placebo-supplemented groups , respectively . During the overreaching cycle , HMB-FA attenuated increases in CK ( −6 ± 91 vs. 277 ± 229 IU/l , p < 0.001 ) and cortisol ( −0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl , p < 0.003 ) in the HMB-FA- and placebo-supplemented groups , respectively . Conclusions These results suggest that HMB-FA  enhances hypertrophy , strength , and power following chronic resistance training , and prevents decrements in performance following the overreaching Purpose Many physiological maladaptations persist after overreaching and overtraining resistance exercise ( RE ) . However , no studies have investigated changes in mitogen-activated protein kinases ( MAPK ) after overtraining in humans , despite their critical role regulating exercise-induced muscular adaptations . The purpose of this study was to describe the changes in total and resting phosphorylation status of extracellular signal-regulated kinase 1/2 ( ERK1/2 ) , c-Jun NH2-terminal kinase ( JNK ) and p38-MAPK following a period of RE overreaching or overtraining . Methods Following 2–4 weeks of normal training ( low volume/low intensity ) , two groups of males performed either a high-power overreaching protocol ( HPOR n = 6 , mean ± SD , age 23 ± 3.4 years , mass 86.5 ± 17.7 kg , height 1.77 ± 0.06 m ) or high-intensity overtraining protocol ( HIOT n = 8 , age 19.8 ± 1.8 years , mass 76.8 ± 6.7 kg , height 1.8 ± 0.06 m ) . Resting muscle biopsies were obtained at baseline ( BL ; end of normal training period ) and 24 h after the final session of stressful training ( i.e. , HPOR or HIOT programs ) . Total MAPK and ratio of phosphorylated/total (p-MAPK)- ERK1/2 , JNK , and p38-MAPK were analyzed via western blotting . 2 × 2 ( group × time ) ANOVA determined differences in MAPK between BL and post-training protocol s. Results Compared to BL , total-ERK increased after HPOR , but decreased after HIOT ( p ≤ 0.05 ) . p-ERK1/2/total-ERK increased after HIOT ( p ≤ 0.05 ) . The ratio of p-JNK/total-JNK and p-ERK1/2/total-ERK decreased after HPOR ( p ≤ 0.05 ) ; however , this result was primarily due to increased total MAPK content . p-p38-MAPK decreased after HPOR ( p ≤ 0.05 ) . Conclusion Total and p-MAPK are differentially expressed after HPOR and HIOT RE . These changes are likely involved in the maladaptation reported in overreaching and overtraining exercise . This is the first study describing altered MAPK in RE overtrained and overreached humans The injury epidemiology of  competitive power lifters  was investigated to provide a basis for injury prevention initiatives in power lifting . Self-reported retrospective injury data for 1 year and selected biographical and training information were obtained via a 4-page injury survey from 82 men and 19 women of varying ages ( Open and Masters ) , body masses ( lightweight and heavyweight ) , and competitive st and ards ( national and international ) . Injury was defined as any physical damage to the body that caused the lifter to miss or modify one or more training sessions or miss a competition . A total of 118 injuries , which equated to 1.2 ± 1.1 injuries per lifter per year and 4.4 ± 4.8 injuries per 1,000 hours of training , were reported . The most commonly injured body regions were the shoulder ( 36 % ) , lower back ( 24 % ) , elbow ( 11 % ) , and knee ( 9 % ) . More injuries appeared to be of a sudden ( acute ) ( 59 % ) rather than gradual ( chronic ) nature ( 41 % ) . National competitors had a significantly greater rate of injury ( 5.8 ± 4.9 per 1,000 hours ) than international competitors ( 3.6 ± 3.6 per 1,000 hours ) . The relative proportion of injuries at some body regions varied significantly as a function of competitive st and ard and gender . No significant differences in injury profile were seen between Open and Masters or between lightweight and heavyweight lifters . Power lifting appears to have a moderately low risk of injury , regardless of the lifter 's age , body mass , competitive st and ard , or gender , compared with other sports . Future research should utilize a prospect i ve cohort or case-controlled design to examine the effect of a range of other intrinsic and extrinsic factors on injury epidemiology and to assess the effects of various intervention strategies Seventeen weight-trained males were divided into an  overtraining group [ OT ; n = 11 ; age = 22.0 + /- 0.9 ( SE ) yr ] that weight trained their legs daily for 2 wk with 100 % 1 repetition maximum relative intensity on a squat machine and a control group ( n = 6 ; age = 23.7 + /- 2.4 yr )  that exercised 1 day/wk with low relative intensity ( 50 % 1 repetition maximum ) . Test batteries including strength assessment s and resting and exercise-induced concentrations of epinephrine and norepinephrine were conducted at the beginning , middle , and end ( tests 1 - 3 , respectively ) of the study . Strength capabilities decreased by test 3 for the OT group ( P < 0.05 ) . Resting catecholamine concentrations did not change for either group during the study , whereas exercise-induced concentrations of both epinephrine ( test 1 = 3,407.9 + /- 666.6 pmol/l , test 2 = 7,563.7 + /- 1,210.6 pmol/l , test 3 = 6,931.6 + /- 919.3 pmol/l ) and norepinephrine ( test 1 = 42.9 + /- 7.4 nmol/l , test 2 = 70.0 + /- 8.8 nmol/l , test 3 = 85.2 + /- 14.5 nmol/l ) significantly increased by tests 2 and 3 for only the OT group . Correlation coefficients suggested decreased responsitivity of skeletal muscle to sympathetic nervous system activity . It appears that altered exercise-induced sympathetic nervous system activity accompanies high relative intensity resistance exercise overtraining and may be among the initial responses to the onset of the previously theoretical sympathetic overtraining syndrome The purpose of this investigation was to study a high-intensity resistance exercise overtraining protocol result ing in muscular strength decrements .  Seventeen weight-trained males were divided into an  overtraining group ( OT ; N = 11 ; mean + /- SE , age = 22.0 + /- 0.9 yr , )  that exercised on a squat machine daily for 2 wk with 100 % of 1 repetition maximum ( RM ) relative intensity , and a control group ( CON ; N = 6 ; age = 23.7 + /- 2.4 yr )  that exercised 1 d.wk-1 with low intensity ( 50 % 1 RM ) . Test batteries were conducted at the beginning ( test 1 ) , after 1 wk ( test 2 ) , and after 2 wk ( test 3 ) of the study . One RM performance significantly decreased from test 1 to test 3 ( P < 0.05 ) for the OT group ( mean = -12.2 + /- 3.8 kg ) , but not the CON group ( mean = -1.1 + /- 0.8 kg ) . Isokinetic and stimulated isometric muscle force significantly decreased for the OT group compared with the CON group by test 3 . The primary site of maladaptation appeared to be in the periphery as indicated by changes in stimulated force , circulating CK activity , and exercise-induced lactate responses . This protocol produced a significant decrease in 1 RM performance , thus providing a model for the study of short-term , high-intensity resistance exercise overtraining To examine the effects of 1 week of high volume weightlifting and amino acid supplementation , 28 elite junior male weightlifters received either amino acid ( protein ) or lactose ( placebo ) capsules using double-blind procedures . Weightlifting test sessions were performed before and after 7 days of high volume training sessions . Serum concentrations of testosterone ( Tes ) , cortisol ( Cort ) , and growth hormone ( GH ) as well as whole blood lactate ( HLa ) were determined from blood draws . Lifting performance was not altered for either group after training , although vertical jump performance was not altered for either group after training , although vertical jump performance decreased for both groups . Both tests elicited significantly elevated exercise-induced hormonal and HLa concentrations . Significant decreases in postexercise hormonal and HLa concentrations from Test 1 to Test 2 were observed for both groups . Tes concentrations at 7 a.m. and preexercise decreased for both groups from Test 1 to Test 2 , while the placebo group exhibited a decreased 7 a.m. Tes/Cort . These data suggest that amino acid supplementation does not influence resting or exercise-induced hormonal responses to 1 week of high volume weight training , but endocrine responses did suggest an impending over-training syndrome The purpose of this investigation was to examine the effects of amino acid supplementation on muscular performance and resting hormone concentrations during resistance training overreaching . Seventeen resistance-trained men were r and omly assigned to either an amino acid ( AA ) or a placebo ( P ) group and underwent 4 weeks of total-body resistance training design ed to induce a state of overreaching . The protocol consisted of two 2-week phases ( phase 1 , 3 sets of 8 exercises performed for 8 - 12 repetitions ; phase 2 , 5 sets of 5 exercises performed for 3 - 5 repetitions ) . Muscle strength and resting blood sample s were determined before ( 
    Output:
    
Few studies have appropriately established FOR , NFOR or OTS in resistance training .
Overtraining may be related to frequent high-intensity and monotonous resistance training .
However , no marker other than a sustained decrease in performance has been established as a reliable indicator of overtraining in resistance exercise .