Biomedical subjects

Jay R Hoffman

Publications and source records attributed to Jay R Hoffman.

At least 19 recordsLinked to original sources

PubMed2007

Inhalation of ultrafine and fine particulate matter disrupts systemic vascular function.

This study investigated the effects of particulate matter (PM) with aerodynamic diameter 0.02-1 microm (noted as PM1) inhalation during exercise on conduit artery and microvascular function. Inhalation of internal combustion-derived PM is associated with cardiovascular mortality and morbidity. Direct action of PM on the vascular endothelium is likely, as a substantial fraction of ultrafine PM translocates from the alveoli to the circulatory system. Sixteen intercollegiate athletes performed 30 min of exercise while inhaling low or high PM1. Flow-mediated brachial artery dilation (FMD) using high-resolution ultrasonography with simultaneous measurements of forearm oxygen kinetics using near infrared spectrophotometry (NIRS) was done before and after exercise. Basal brachial artery vasoconstriction was found after high PM1 exercise (4.0%, 4.66 +/- 0.609 to 4.47 +/- 0.625 mm diameter; p = .0002), but not after low PM1 exercise (-0.3%, 4.66 +/- 0.626 to 4.68 +/- 0.613 mm diameter). FMD was impaired after high PM1 exercise (6.8 +/- 3.58% for preexercise FMD and 0.30 +/- 2.74% for postexercise FMD, p = .0001), but not after low PM1 exercise (6.6 +/- 4.04% for preexercise FMD and 4.89 +/- 4.42% for postexercise FMD). Reduction in forearm muscle reperfusion estimated by reoxygenation slope-to-baseline after 4 min cuff ischemia was observed for high PM1 exercise (55% vs. 3%, p = .0006); no difference was noted for low PM1 exercise. Brachial artery FMD was significantly correlated to muscle reoxygenation slope-to-baseline (r = .50, p = .005). Acute inhalation of high [PM1] typical of urban environments impairs both systemic conduit artery function and microcirculation. The observed decrease reoxygenation slope-to-baseline after cuff release is consistent with reduced blood flow in the muscle microvasculature.

Administration, Inhalation↗

PubMed2006

Anticipatory responses of catecholamines on muscle force production.

Few data exist on the temporal relationship between catecholamines and muscle force production in vivo. The purpose of this study was to examine the influence of preexercise arousal on sympathoadrenal neurohormones on muscular force expression during resistance exercise. Ten resistance-trained men completed two experimental conditions separated by 7 days: 1) acute heavy resistance exercise protocol (AHREP; 6 x 10 repetitions parallel squats, 80% 1 repetition maximum) and 2) control (Cont; rest). Peak force (F(peak)) was recorded during a maximal isometric squat preceding each set and mean force (F(mean)) was measured during each set. Serial venous blood samples were collected before the AHREP and immediately preceding each set. Blood collection times were matched during Cont. Preexercise epinephrine (Epi), norepinephrine (NE), and dopamine (DA) increased (P or= 0.05) in muscular performance (F(peak), F(mean)) during AHREP and that five subjects (F(reducers)) had significant reductions in F(peak) and F(mean). Integrated area under the curve for Epi, NE, and F(peak) were greater (P < 0.02) for F(maintainers) than F(reducers). In conclusion, an anticipatory rise in catecholamines existed, which may be essential for optimal force production at the onset of exercise.

Adult↗

PubMed2006

Pituitary-adrenal responses to arm versus leg exercise in untrained man.

The purpose of this study was to examine pituitary-adrenal (PA) hormone responses [beta-endorphin (beta-END), adrenocorticotropic hormone (ACTH) and cortisol] to arm exercise (AE) and leg exercise (LE) at 60 and 80% of the muscle-group specific VO2 peak. Eight healthy untrained men (AE VO2 peak=32.4+/-3.0 ml kg(-1) min(-1), LE VO2 peak=46.9+/-5.3 ml kg(-1) min(-1)) performed two sub-maximal AE and LE tests in random order. Plasma beta-END, ACTH and cortisol were not different (P>0.05) between AE and LE at either exercise intensity; the 60% testing elicited no changes from pre-exercise (PRE) values. For 80% testing, plasma beta-END, ACTH and cortisol were consistently, but not significantly, greater during LE than AE. In general, plasma beta-END and ACTH were higher (P<0.05) during 80% exercise, than PRE, for both AE and LE. Plasma cortisol was elevated (P<0.05) above PRE during 80% LE, and following 80% for both AE and LE. Plasma ACTH was higher (P<0.05) during 80% LE and AE versus 60% LE and AE, respectively. Plasma beta-END and cortisol were significantly higher during and immediately after 80% LE than 60% LE. Thus, plasma beta-END, ACTH and cortisol responses were similar for AE and LE at the two relative exercise intensities, with the intensity threshold occurring somewhere between 60 and 80% of VO2 peak. It appears that the smaller muscle mass associated with AE was sufficient to stimulate these PA axis hormones in a manner similar to LE, despite the higher metabolic stress (i.e., plasma La-) associated with LE.

Adrenocorticotropic Hormone↗

PubMed2005

Metabolic and perceptual responses during Spinning cycle exercise.

PURPOSE: The present investigation was undertaken to compare metabolic and perceptual responses between exercise performed at constant intensity (CON) and with a Spinning protocol of variable intensity (VAR). METHOD: Fifteen subjects, including seven males and eight females (23 +/- 5 yr, 72 +/- 17 kg, and 171 +/- 10 cm), underwent two experimental trials. During each trial, subjects performed a 30-min cycle exercise protocol that was followed by a 30-min recovery period. Exercise was performed at 67 +/- 3% (means +/- SD) of HR(max) in CON. In VAR, the similar intensity (68 +/- 4% HR(max)) was also achieved, although the protocol entailed alternating phases of both higher and lower intensity arranged similarly to what is designed for a typical Spinning workout. Oxygen uptake (VO2) and HR were measured at rest and throughout both exercise and recovery, whereas RPE were recorded during exercise only. Plasma lactate concentrations [La] were determined at rest, the end of exercise, and the end of recovery. RESULTS: No differences in average VO2, HR, and RPE were found during exercise between CON and VAR. However, average VO2 and HR were higher (P < 0.05) in VAR than CON (0.33 +/- 0.03 vs 0.26 +/- 0.02 L x min(-1) and 91 +/- 3 vs 80 +/- 2 beats x min(-1), respectively). [La] was higher (P < 0.05) at the end of exercise in VAR than CON (7.2 +/- 0.8 vs 2.7 +/- 0.3 mmol x L(-1)), but became similar at the end of recovery. CONCLUSION: An exercise regimen in which intensity varies exerts no added effect on metabolic and perceptual responses during exercise as long as the average intensity is kept the same. However, VAR resulted in a greater [latin capital V with dot above]O2 after exercise, and this augmented postexercise oxygen consumption may be mediated in part by elevated plasma [La].

Adult↗

PubMed2005

Biochemical and hormonal responses during an intercollegiate football season.

PURPOSE: Changes in biochemical indices of muscle damage and hormonal markers of stress were examined during a competitive intercollegiate football season. METHODS: Twenty-one members of an NCAA Division III football team volunteered to serve as subjects. Eleven of these subjects were starters (ST) and 10 were non-starters (NS). All subjects reported to the Human Performance Laboratory on five separate occasions for blood draws. The first testing session (T1) occurred 1 d before the start of pre-season training camp, the second testing session (T2) occurred at the end of training camp (10 d later), and the other three testing sessions occurred at weeks 3 (T3), 7 (T4), and 11 (T5) of the competitive season. RESULTS: Significant elevations in creatine kinase (CK) were seen from T1 to T2 in both ST and NS. ST had significantly higher CK concentrations at T2 than NS. CK concentrations for both groups returned to baseline levels by T3 and remained constant for the rest of the season. No significant between-group differences were seen in myoglobin (MB), testosterone (TE), cortisol (C), or the testosterone/cortisol ratio (T/C) during the season. A significant main effect for time was seen for C and T/C. C concentrations were significantly lower at T2 than at T1, T3, T4, and T5. Similar changes were also seen for T/C. CONCLUSION: CK elevations seen during T2 appear to reflect the high intensity and physical nature of training camp. However, biochemical and endocrine responses during a season of intercollegiate football competition suggest a degree of sensitization (contact adaptation) of the muscles relating to the repeated traumas occurring during the season.

Adult↗

PubMed2005

Evaluation of physiological responses during recovery following three resistance exercise programs.

The present study was conducted to examine (a) whether there is an association between maximal oxygen uptake (Vo(2)max) and reduction in postexercise heart rate (HR) and blood lactate concentrations ([La]) following resistance exercise and (b) how intensity and Volume of resistance exercise affect postexercise Vo(2). Eleven regularly weight-trained males (20.8 +/- 1.3 years; 96.2 +/- 14.4 kg, 182.4 +/- 7.3 cm) underwent 4 sets of squat exercise on 3 separate occasions that differed in both exercise intensity and volume. During each testing session, subjects performed either 15 repetitions.set(-1) at 60% of 1 repetition maximum (1RM) (L), 10 repetitions.set(-1) at 75% of 1RM (M), or 4 repetitions.set(-1) at 90% of 1RM (H). During each exercise, Vo(2) and HR were measured before (PRE), immediately post (IP), and at 10 (10P), 20 (20P) 30 (30P), and 40 (40P) minutes postexercise. The [La] was measured at PRE, IP, 20P, and 40P. Decrease in HR (DeltaHR) was determined by subtracting HR at 10P from that at IP, whereas decrease in [La] (Delta[La]) was computed by subtracting [La] at 20P from that at IP. A significant correlation (p < 0.05) was found between Vo(2)max and DeltaHR in all exercise conditions. A significant correlation (p < 0.05) was also found between Vo(2)max and Delta[La] in L and M but not in H. The Vo(2) was higher (p < 0.05) during M than H at IP and 10P, while no difference was seen between L and M and between L and H. These results indicate that those with greater aerobic capacity tend to have a greater reduction in HR and [La] during recovery from resistance exercise. In addition, an exercise routine performed at low to moderate intensity coupled with a moderate to high exercise volume is most effective in maximizing caloric expenditure following resistance exercise.

Adaptation, Physiological↗

PubMed2005

The effect of a competitive collegiate football season on power performance and muscle oxygen recovery kinetics.

Ten intercollegiate football players were tested within 3 days prior to (T1) and the day following the end (T2) of football preseason training camp and during weeks 7 (T3) and 11 (T4) of the competitive season. During each testing session, subjects performed a 30-second Wingate anaerobic power test. Near-infrared continuous wave spectroscopy was used to measure muscle deoxygenation during exercise. No changes in any power performance measures were seen during the competitive football season. A significant (p < 0.05) decrease in the extent of deoxygenation during exercise was observed between T2 (72.6 +/- 19.4%) and T4 (50.2 +/- 14.2%). A 30 and 29% difference (p < 0.05) in the onset of reoxygenation was observed between T1 and T3 and T4, respectively. A 51% decrease (p < 0.05) in halftime recovery was observed between T2 and T3. Results indicate that the extent of muscle deoxygenation is reduced during high-intensity exercise and that muscle oxygen recovery kinetics improves over the duration of a competitive season of football.

Adult↗

PubMed2005

Effect of low-dose, short-duration creatine supplementation on anaerobic exercise performance.

To examine the efficacy of a low-dose, short-duration creatine monohydrate supplement, 40 physically active men were randomly assigned to either a placebo or creatine supplementation group (6 g of creatine monohydrate per day). Testing occurred before and at the end of 6 days of supplementation. During each testing session, subjects performed three 15-second Wingate anaerobic power tests. No significant (p > 0.05) group or time differences were observed in body mass, peak power, mean power, or total work. In addition, no significant (p > 0.05) differences were observed in peak power, mean power, or total work. However, the change in the rate of fatigue of total work was significantly (p < 0.05) lower in the creatine supplementation group than in the placebo group, indicating a reduced fatigue rate in subjects supplementing with creatine compared with the placebo. Although the results of this study demonstrated reduced fatigue rates in patients during high-intensity sprint intervals, further research is necessary in examining the efficacy of low-dose, short-term creatine supplementation.

Adult↗

PubMed2005

Comparison of loaded and unloaded jump squat training on strength/power performance in college football players.

The purpose of this study was to explore the effects of 5 weeks of eccentrically loaded and unloaded jump squat training in experienced resistance-trained athletes during the strength/ power phase of a 15-week periodized off-season resistance training program. Forty-seven male college football players were randomly assigned to 1 of 3 groups. One group performed the jump squat exercise using both concentric and eccentric phases of contraction (CE; n = 15). A second group performed the jump squat exercise using the concentric phase only (n = 16), and a third group did not perform the jump squat exercise and served as control (CT; n = 16). No significant differences between the groups were seen in power, vertical jump height, 40-yd sprint speed and agility performance. In addition, no differences between the groups were seen in integrated electromyography activity during the jump squat exercise. Significant differences between the CE and CT groups were seen in Delta 1RM squat (65.8 and 27.5 kg, respectively) and Delta 1RM power clean (25.9 and 3.8 kg, respectively). No other between-group differences were observed. Results of this study provide evidence of the benefits of the jump squat exercise during a short-duration (5-week) training program for eliciting strength and power gains. In addition, the eccentric phase of this ballistic movement appears to have important implications for eliciting these strength gains in college football players during an off-season training program. Thus, coaches incorporating jump squats (using both concentric and eccentric phases of contraction) in the off-season training programs of their athletes can see significant performance improvements during a relatively short duration of training.

Adult↗

PubMed2004

Timing of preparatory landing responses as a function of availability of optic flow information.

This study investigated temporal patterns of EMG activity during self-initiated falls with different optic flow information ('gaze directions'). Onsets of EMG during the flight phase were monitored from five experienced volunteers that completed 72 landings in three gaze directions (downward, mid-range and horizontal) and six heights of fall (10-130 cm). EMG recordings were obtained from the right gastrocnemius, tibialis anterior, biceps femoris and rectus femoris muscles, and used to determine the latency of onset (L(o)) and the perceived time to contact (T(c)). Impacts at touchdown were also monitored using as estimates the major peak of the vertical ground reaction forces (F(max)) normalized to body mass, time to peak (T(max)), peak impulse (I(norm)) normalized to momentum, and rate of change of force (dF(max)/dt). Results showed that L(o) was longer as heights of fall increased, but remained within a narrow time-window at >50 cm landings. No significant differences in L(o) were observed when gaze direction was changed. The relationship between T(c) and flight time followed a linear trend regardless of gaze direction. Gaze direction did not significantly affect the landing impacts. In conclusion, availability of optic flow during landing does not play a major role in triggering the preparatory muscle actions in self-initiated falls. Once a structured landing plan has been acquired, the relevant muscles respond relative to the start of the fall.

Adult↗

PubMed2004

Effects of beta-hydroxy beta-methylbutyrate on power performance and indices of muscle damage and stress during high-intensity training.

Twenty-six members of a collegiate football team were randomly assigned to either a supplement (S) (3 g of beta-hydroxy beta-methylbutyrate [HMB] per day) or placebo (P) group. Testing occurred before (PRE) and at the end of 10 days of preseason football training camp (POST). During each testing session, subjects performed an anaerobic power test, and blood samples were obtained for testosterone, cortisol, creatine kinase, and myoglobin analysis. No differences in anaerobic power were seen between PRE and POST in either group. Cortisol concentrations were significantly decreased from PRE (333 +/- 81 nmol.L(-1)) to POST (246 +/- 79 nmol.L(-1)), and a sixfold increase was seen in creatine kinase concentrations at POST. However, no significant differences between the groups were seen. No significant time or group effects were observed in testosterone or myoglobin concentrations. Results suggest that short duration HMB supplementation does not provide any ergogenic benefit in collegiate football players during preseason training camp.

Administration, Oral↗

PubMed2004

Comparison of Olympic vs. traditional power lifting training programs in football players.

Twenty members of an National Collegiate Athletic Association Division III collegiate football team were assigned to either an Olympic lifting (OL) group or power lifting (PL) group. Each group was matched by position and trained 4-days.wk(-1) for 15 weeks. Testing consisted of field tests to evaluate strength (1RM squat and bench press), 40-yard sprint, agility, vertical jump height (VJ), and vertical jump power (VJP). No significant pre- to posttraining differences were observed in 1RM bench press, 40-yard sprint, agility, VJ or in VJP in either group. Significant improvements were seen in 1RM squat in both the OL and PL groups. After log10-transformation, OL were observed to have a significantly greater improvement in Delta VJ than PL. Despite an 18% greater improvement in 1RM squat (p > 0.05), and a twofold greater improvement (p > 0.05) in 40-yard sprint time by OL, no further significant group differences were seen. Results suggest that OL can provide a significant advantage over PL in vertical jump performance changes.

Football↗

PubMed2003

Effect of order of exercise intensity upon cardiorespiratory, metabolic, and perceptual responses during exercise of mixed intensity.

Exercise of mixed intensities can be of benefit in many different ways. However, whether physiological interaction exists between exercises of different intensity is questionable. As such, the primary aim of this study was to examine the effect of order of exercise intensity upon cardiorespiratory, metabolic, and perceptual responses during exercise of mixed intensity. Eight males and four females volunteered to serve as subjects for the study. They were informed of the purpose of the experiment and gave their written consent to participate. Each subject completed a peak oxygen uptake ( VO(2peak)) test and two submaximal exercises of mixed intensity on three separate laboratory visits. During each submaximal exercise trial, subjects performed a 15-min (high intensity) exercise at 70% VO(2peak) that was followed by another 15-min (low intensity) exercise at 50% VO(2peak) (high/low, H/L), or a 15-min exercise at 50% VO(2peak) that was followed by another 15-min exercise at 70% VO(2peak) (low/high, L/H). Oxygen uptake ( VO(2)), respiratory exchange ratio ( R), expired ventilation ( V(E)), heart rate (HR) and ratings of perceived exertion (RPE) were measured every 5 min throughout exercise. Energy expenditure and carbohydrate and fat oxidation were calculated from VO(2) adjusted for substrate metabolism using R and then accumulated for each phase of exercise intensity as well as for the entire exercise session. VO(2) and HR were higher ( P<0.05), while R was lower ( P<0.05) at the lower intensity in H/L than in L/H. V(E) and RPE were lower ( P<0.05) at the higher intensity in H/L than in L/H. While no differences in caloric expenditure and carbohydrate oxidation between the two trials were observed, fat oxidation was higher ( P<0.05) both at the lower intensity and for the entire trial in H/L than in L/H. It appears that during exercise of mixed intensity, placing some periods of moderate intensity exercise prior to a milder one is a more favorable sequence in that it can elicit a greater fat oxidation while being felt less stressful.

Adipose Tissue↗

PubMed2003

Regulating intensity using perceived exertion during extended exercise periods.

The present study was undertaken to examine the validity of using the OMNI scale of perceived exertion to regulate intensity during extended exercise periods. Forty-eight subjects (24 male, 24 female) were recruited and each subject completed a maximal graded exercise test (GXT) and two 20-min submaximal exercises. During the GXT, ratings of perceived exertion (RPE) as well as oxygen uptake (VO(2)) and heart rate (HR) equivalent to 50 and 70% of maximum VO(2) (VO(2max)) were estimated. During each submaximal exercise, subjects were instructed to produce and maintain a workload equivalent to the RPE estimated at 50 or 70% VO(2max), and VO(2) and HR were measured every 5 min throughout the exercise. Of the 48 subjects, 12 (6 male and 6 female) performed both the estimation and production trials on a treadmill (TM/TM), 12 (6 male and 6 female) performed both the estimation and production trials on a cycle ergometer (C/C), 12 (6 male and 6 female) performed the estimation trial on a treadmill and the production trial on a cycle ergometer (TM/C), and 12 (6 male and 6 female) performed the estimation trial on a cycle ergometer and the production trial on a treadmill (C/TM). No differences in VO(2) between the estimation and any 5 min of the production trial were observed at either intensity in TM/TM and C/C. No differences in HR between the estimation and any 5 min of the production trial were also observed at 50% VO(2max) in TM/TM and at both 50 and 70% VO(2max) in C/C. However, HR was higher at 20th min of the production trial at 70% VO(2max) in TM/TM. Both the VO(2) and HR were generally lower in TM/C and higher in C/TM. However, these differences diminished when values were normalized using VO(2max) of the same mode that other groups had attained. These data suggest that under both intra- and intermodal conditions, using the OMNI perceived exertion scale is effective not only in establishing the target intensity at the onset of exercise, but also in maintaining the intensity throughout a 20-min exercise session.

Adaptation, Physiological↗

PubMed2003

Cognitive and motor function after administration of hydrocodone bitartrate plus ibuprofen, ibuprofen alone, or placebo in healthy subjects with exercise-induced muscle damage: a randomized, repeated-dose, placebo-controlled study.

RATIONALE: Medications combining hydrocodone bitartrate and non-steroidal anti-inflammatory agents appear more beneficial than anti-inflammatory medications alone in treating pain and inflammation from acute soft tissue trauma, but opiate side effects may include sedation and impaired cognitive and motor performance. OBJECTIVE: Performance on complex cognitive and motor tasks was evaluated in healthy subjects with exercise-induced muscle damage who were treated with a hydrocodone-ibuprofen combination, ibuprofen alone, or placebo. METHODS: This double-blind, randomized, placebo-controlled, repeated-dose clinical trial compared the effects of hydrocodone bitartrate (7.5 mg) plus ibuprofen (200 mg), ibuprofen alone, and placebo on cognitive and motor function in 72 healthy college men. Muscle damage in the quadriceps of each subject's dominant leg was induced by an eccentric exercise protocol. Subjects took the study medication four times daily (every 4-6 h) for 5 days. Forty minutes after medication ingestion at the same time each day, subjects underwent tests of attention/concentration, motor performance, and reaction time. Four trained assessors rotated among subjects so that none tested the same participant on more than three occasions. RESULTS: Repeated measures analyses of covariance revealed no between-group differences on a complex memory and cognition task or complex reaction time. Subjects using hydrocodone bitartrate plus ibuprofen performed significantly less well on a simple tracking task and made significantly more errors on a simple reaction-time task than the other two groups. These deficits were found to be highly transitory and not related to confusion or fatigue. CONCLUSION: Hydrocodone plus ibuprofen was not associated with deterioration in complex cognition but was related to very transitory decrements in tasks involving simple hand-eye coordination.

Adolescent↗

PubMed2003

The effect of an intercollegiate soccer game on maximal power performance.

The effect of a competitive soccer match on maximal power performance was assessed on 19 members of an NCAA Division III female soccer team. Performance testing occurred within 24 hours prior to the game (Pre), immediately postgame (IP), and 24 hours postgame (24P). Each subject performed a squat jump (SJ) and countermovement jump (CMJ). Comparisons between starters (n = 10) and nonstarters (n = 9) revealed no between-group differences in power performance at IP, but starters were found to have significantly lower power and force measures at 24P than nonstarters. There were significant correlations between playing time and peak force during the SJ at 24P (r = -0.47), and between playing time and peak power during the SJ at IP (r = -0.57) and 24P (r = -0.51), and during the CMJ at IP (r = -0.49). Comparisons between different positions revealed no differential fatigue patterns. Results of this study show that power performance appears to be maintained for the duration of a soccer match but declines significantly within 24 hours after the match. Position played does not appear to affect performance decrements seen at 24 hours postmatch.

Adult↗

PubMed2003

Effect of muscle oxygenation during resistance exercise on anabolic hormone response.

PURPOSE: The mechanisms that underlie the affect of acute program variables on muscle growth and strength development for strength/power athletes have been of great interest. This investigation examined the affects of two different resistance exercise protocols on muscle oxygenation, and the anabolic hormonal response to such exercise. METHODS: Eleven experienced resistance-trained male athletes performed four sets of the squat exercise using either a low-intensity, high-volume (LI; 15 repetitions at 60% one-repetition maximum [1-RM]) or high-intensity, low-volume (HI; 4 repetitions at 90% 1-RM) load. Venous blood samples were obtained before (Pre), immediate (IP), 20- (20P), and 40-min (40P) postexercise. Continuous-wave near-infrared spectroscopy was used to measure oxygen desaturation during exercise. RESULTS: No differences in muscle deoxygenation were seen between LI and HI. However, time-dependent postexercise reoxygenation was significantly different between the two exercise sessions (35.3 +/- 17.4 s vs 24.5 +/- 14.3 s in LI and HI, respectively). Testosterone and growth hormone (GH) concentrations were significantly elevated from Pre at IP, 20P, and 40P in both LI and HI. GH concentrations were higher (P<0.05) for LI than at HI at 20P and 40P. CONCLUSION: Muscle oxygen recovery kinetics appeared to be influenced by differences in the intensity and volume of exercise, and delayed reoxygenation appears to affect the GH response to exercise.

Adult↗

PubMed2003

Strength changes during an in-season resistance-training program for football.

The purpose of this study was to examine the effects of both intensity and volume of training during a 2 d.wk(-1) in-season resistance-training program (RTP) for American football players. Fifty-three National Collegiate Athletic Association Division III football players were tested in the 1 repetition maximum (1RM) bench press and 1RM squat on the first day of summer training camp (PRE) and during the final week of the regular season (POST). Subjects were required to perform 3 sets of 6-8 repetitions per exercise. Significant strength improvements in squat were observed from PRE (155.0 +/- 31.8 kg) to POST (163.3 +/- 30.0 kg), whereas no PRE to POST changes in bench press were seen (124.7 +/- 21.0 kg vs.123.9 +/- 18.6 kg, respectively). Training volume and training compliance were not related to strength improvement. Further analysis showed that athletes training at >or=80% of their PRE 1RM had significantly greater strength improvements than athletes training at <80% of their PRE 1RM, for both bench press and squat. Strength improvements can be seen in American football players, during an in-season RTP, as long as exercise intensity is >or=80% of the 1RM.

Adult↗