Search

Inherited acidosis may result from a primary renal defect in acid-base handling, emphasizing the central role of the kidney in control of body pH; as a secondary phenomenon resulting from abnormal renal electrolyte handling; or from excess production of acid elsewhere in the body. Here, we review our current understanding of the inherited renal acidoses at a genetic and molecular level.

The purpose of this study was to determine the acute effects of a spectrum of eccentric loads on force, velocity, and power during the concentric portion of maximal-effort jump squats utilizing a repeated measures design. Thirteen resistance-trained men (age = 22.8 +/- 2.9 years, weight = 87.1 +/- 11.8 kg, 163.5 +/- 28.6 kg squat 1 repetition maximum [1RM]; mean +/- SD), who routinely incorporated back squats into their training, participated as subjects in this investigation. Jump squat performance was assessed using 4 experimental conditions. The first of these conditions consisted of an isoinertial load equal to 30% of back squat 1RM. The remaining conditions consisted of jump squats with a concentric load of 30% 1RM, subsequent to the application of experimental augmented eccentric loading (AEL) conditions of 20, 50, and 80% of back squat 1RM, respectively. All subjects performed 2 sets of 1RM of maximum-effort jump squats with all experimental conditions in a counter-balanced sequence. Forty-eight hours after completing the first testing session, subjects repeated the experimental testing protocol to establish stability reliability. Peak performance values for the reliable variables of force, velocity, and power, as well as force and power values obtained at 20-ms intervals during the initial 400 ms of the concentric jump squat range of motion, showed no statistical difference (p > 0.05) across the experimental AEL loads. These results suggest that load-spectrum AEL prior to a 30% 1RM jump squat fails to acutely enhance force, velocity, and power.

Purpose: The purpose of this investigation was to measure the oxidative stress response to similarly matched work bouts of squat and sprint exercise. Methods: Twelve anaerobically trained men performed six 10-s sprints and, on a separate occasion, repeated barbell squats to approximately equal the amount of work performed during the sprints. Blood lactate, heart rate, and perceived exertion was measured before and following each exercise bout. Muscle soreness, muscle force, and creatine kinase activity was determined preexercise and through 48 h of recovery. Desmin cytoskeletal protein was determined via muscle biopsy of the vastus lateralis before and at 24 h following each exercise. Plasma protein carbonyls (PC) and malondialdehyde (MDA) were measured as biomarkers of oxidative stress. Results: Heart rate and perceived exertion was not different between exercise sessions (P > 0.05), although lactate was higher following sprinting compared with squatting (P = 0.002). Muscle soreness was greater for squatting than sprinting (P = 0.003) and reached a peak immediately postexercise for both sessions (P = 0.0003). Muscle force was unaffected by either exercise session (P > 0.05), and creatine kinase activity was elevated to a similar extent following both sessions. Desmin-negative fibers were virtually nonexistent after either exercise bout, indicating no loss of this cytoskeletal protein. Neither PC nor MDA was affected by the exercise (P > 0.05). Conclusion: These results suggest that in anaerobically trained men, the oxidative stress and muscle injury response to similarly matched anaerobic exercise bouts is minimal, and not different between exercise modes. Furthermore, when compared with previous literature on untrained subjects, the response is significantly attenuated, possibly because of adaptations occurring as a result of chronic, strenuous anaerobic training.

The purpose of this study was to determine if supplementation with a liquid multi-vitamin/mineral would improve anaerobic exercise performance. Fourteen resistance-trained men performed a 30-second cycle sprint and one set of squat exercise on 2 separate days before and following 8 weeks of supplementation with either a liquid multi-vitamin/ mineral or a placebo. Heart rate, perceived exertion, blood lactate, peak and mean power, and rate of fatigue were determined for all tests. No differences were noted for any variable (P > 0.05). When controlling for presupplementation values, however, a decreased rate of fatigue was noted for both exercise tests following the multi-vitamin/mineral supplementation. These data suggest that in resistance trained men consuming a nutritionally sound diet, supplementation with a liquid multi-vitamin/mineral does not favorably impact most anaerobic exercise performances. Such supplementation, however, may result in a minor decreased rate of fatigue. It appears that, in terms of improved short duration anaerobic exercise performance, supplemental micronutrients may not be efficient ergogenic agents for well-trained individuals consuming an adequate diet.

Thirty-six healthy men with varying degrees of physical training background performed maximal-effort isometric and isoinertial knee extensor actions, with relative loads equal to 40% and 70% of one-repetition maximum. Force, velocity, and power were derived from force and linear position transducers at 500 Hz. Biopsies were taken from the vastus lateralis and analyzed by SDS-PAGE for relative myosin heavy chain (MHC) content. Relative MHC IIx content was included in a regression model, and explained variance noted. Relative MHC I content was subsequently added to the regression model to determine what, if any, additional variance was explained beyond that of MHC IIx. Results indicated that no relationship (r = 0.0 to 0.1) exists between the relative expression of MHC isoforms from the vastus lateralis and isometric/isoinertial performance in a population with diverse training backgrounds. Lack of nervous system adaptations in the untrained subjects in the study possibly attenuates the significant relationship between MHC and in-vivo muscle performance previously established in trained populations.

Speakers at the course were given vignettes describing one or more clinical scenarios on which to base their talks, selected because they represent common but challenging problems likely to be encountered by any physician practising in general internal medicine. Three of the subjects covered – weird thyroid function tests, difficult gout, and dementia – are presented here.

This investigation estimated the amount of variance in voluntary in vivo muscle performance that can be explained by relative myosin heavy chain (MHC) isoform expression. The role of the relative expression of these proteins in relation to in vitro force and velocity performance is well understood, but the in vivo model is less clear. Twenty-two men and women (mean ± SD age, 27 ± 6 years) performed isometric knee extensor actions in which peak force and rate of force development (RFD) were measured. The results of regression analysis showed that the inclusion of MHC IIb explained a significant (19.9%, p < 0.05) amount of variance in relative peak force (adjusted for muscle mass) and 14.1% of the variance in the first half of the rise phase of the force-time curve (RFD0�50%) (p < 0.1). The addition of MHC I into this model explained a significant (p < 0.05) amount of variance above that accounted for by MHC IIb in RFD (45.4%), RFD0�50% (50.8%), and RFD50�100% (second half of the rise phase of the force-time curve) (37.4%). Since the percentage of MHC IIb is reduced rather quickly with training, these data suggest that peak force may also be affected quickly by training. The percentage of MHC I has a longer course for change with training; therefore, it may be inferred that the greatest changes in RFD variables will likely occur during a longer course.

Strength augmentation has been demonstrated in resistance-trained men subsequent to 4 days of training abstinence. However, this phenomenon was exhibited in an unusual circumstance in which the exercise test (seated heel raise) primarily involved an isolated skeletal muscle (soleus) that is normally comprised almost exclusively of 1 fiber type. It is unclear if similar results would be found for aggregate muscle actions. Therefore, a comparable study was designed with this in mind. Subjects were apparently healthy, young, strength-trained men (n = 25). All performed various tests of bench press strength at the beginning of their last standardized dynamic constant external resistance (DCER) training session. Subjects were subsequently randomly assigned to 1 of 4 groups and repeated the identical tests at intervals of either 2, 3, 4, or 5 days with no intervening training. Strength tests consisted of 1 repetition maximum (1RM) concentric-only isokinetic bench presses performed at 1.49 and 0.37 m.s(-1) as well as a 1RM DCER bench press. Measures of peak force and power were obtained from the isokinetic tests and maximum load from the DCER test. Results were expressed in both absolute and relative (to body weight) terms. Subsequent to the 4 abstinence intervals, groups performed similarly (p > 0.05) for all dependent variables. Concurrently, however, a small effect size (ES) was found for the group having a 4-day respite for both absolute and relative expressions of peak force and power at the slowest isokinetic bench press velocity. A small ES was also identified for the group having 2 days of rest for relative peak force at the slowest isokinetic test velocity and for relative DCER strength. Therefore, modest and transient strength augmentation appears likely in aggregate muscle actions following 2-4 days of training abstinence in resistance-trained men, but only at relatively slow velocities.

Resistance exercise can result in both potentiating and fatiguing responses. These responses can acutely affect performance, which may affect subsequent exercise sessions in the same day. The purpose of this investigation was to study the acute neuromuscular responses to two high intensity training sessions in the same day. Twelve recreationally trained males performed two training sessions, each involving ten sets of five repetitions in the speed squat exercise. For the initial session (HIT-1), the barbell load was constant at 70% one repetition maximum, whereas during the second session (HIT-2), barbell load decreased if movement velocity decreased. Neuromuscular performance testing consisted of unilateral isometric knee extensor actions performed prior to the training day (PRE) and following each testing session. Prior to the sessions, subjects provided a muscle biopsy for myosin heavy chain analysis. Peak force was impaired 16.9 (9.5)% (P approximately 0.00; d=1.62) following HIT-1 and 19.9 (18.4)% (P approximately 0.00; d=1.94) following HIT-2. Initial rate of force development was depressed from PRE following HIT-1 (P approximately 0.00; d=1.74) and HIT-2 (P approximately 0.00; d=2.18); however, this was dependent on muscle fiber composition. Significant correlations existed between the change score for initial rate of force development from HIT-1 to HIT-2 and myosin heavy chain I (r= -0.60; P=0.04) and IIa (r=0.69; P=0.01) expression. Impaired neuromuscular performance following HIT-1 may occur due to low frequency fatigue. For individuals with predominantly myosin heavy chain IIa, HIT-2 appeared to induce post-activation potentiation, resulting in restoration of the initial rate of force development.

Biopsies fro the vastus lateralis muscle of male weightlifters (WL; n=6; X +/- SE, age=27.0 +/- 2.1 years), and non-weight-trained men (CON; n=7; age=27.0 +/- 2.0 years) were compared for fiber types, myosin heavy chain (MHC) and titin content, and fiber type-specific capillary density. Differences (p0.05) were observed for percent fiber types IIC (WL=0.4 +/- 0.2, CON=2.4 +/- 0.8); IIA (WL=50.5 +/- 3.2, CON=26.9 +/- 3.7); and IIB (WL=1.7 +/- 1.4, CON=21.0 +/- 5.3), as well as percent MHC IIa (WL=65.3 +/- 2.4, CON=52.1 +/- 4.2) and percent MHC IIB (WL=0.9 +/- 0.9; CON=18.2 +/- 6.1). All WL exhibited only the titin-1 isoform. Capillary density (caps.mm(-2)) for all fiber types combined was greater for the CON subjects (WL=192.7 +/- 17.3; CON=262.9 +/- 26.3), due primarily to a greater capillary density in the IIA fibers. Weightlifting performances and vertical jump power were correlated with type II fiber characteristics. These results suggest that successful weightlifting performance is not dependent on IIB fibers, and that weightlifters exhibit large percentages of type IIA muscle fibers and MHC IIa isoform content.

To examine the effects of different rest intervals on the repeatability of 1 repetition maximum (1RM) efforts in the free-weight back squat exercise, 17 weight-trained men served as subjects (mean age 22.0 years). One repetition maximum was tested on each of the first 2 days of testing to establish a stable baseline (1RM = 184.9 kg). Each of the next 3 sessions involved performing 2 1RM back squats, with the rest interval between attempted lifts being either 1, 3, or 5 minutes, assigned in a counterbalanced fashion. For the 1-minute rest interval, 13 of 17 subjects successfully completed the second lift; for the 3-minute rest interval, 16 of 17 were successful; and for the 5-minute rest interval, 15 of 17 were successful. Cochran Q analysis determined no significant difference (p0.05) in the ability to repeat a successful maximal-effort back squat when different rest intervals were used. These findings are consistent with the literature for the bench-press exercise and indicate that 1-minute rest intervals are sufficient for recovery between attempted lifts during 1RM testing or training for the free-weight back squat when involving lifters of this caliber.

To determine if training status directly impacted the response to postactivation potentiation, athletes in sports requiring explosive strength (ATH; n = 7) were compared to recreationally trained (RT; n = 17) individuals. Over the course of 4 sessions, subjects performed rebound and concentric-only jump squats with 30%, 50%, and 70% 1 RM loads. Jump squats were performed 5 minutes and 18.5 minutes following control or heavy load warm-ups. Heavy load warm-up consisted of 5 sets of 1 repetition at 90% 1 RM back squat. Jump squat performance was assessed with a force platform and position transducer. Heavy load warm-up did not have an effect on the subjects as a single sample. However, when percent potentiation was compared between ATH and RT groups, force and power parameters were significantly greater for ATH (p0.05). Postactivation potentiation may be a viable method of acutely enhancing explosive strength performance in athletic but not recreationally trained individuals. Reference Data: Chiu, L.Z.F., A.C. Fry, L.W. Weiss, B.K. Schilling, L.E. Brown, and S.L. Smith. Postactivation potentiation response in athletic and recreationally trained individuals.

Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean +/- SD; age = 27.9 +/- 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the toes (restricted). Differences resulted between static knee and hip torques for both types of squat as well as when both squat variations were compared with each other (p0.05). For the unrestricted squat, knee torque (N.m; mean +/- SD) = 150.1 +/- 50.8 and hip torque = 28.2 +/- 65.0. For the restricted squat, knee torque = 117.3 +/- 34.2 and hip torque = 302.7 +/- 71.2. Restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knees and ankles. The squat technique used can affect the distribution of forces between the knees and hips and on the kinematic properties of the exercise.Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.

To examine the skeletal muscle characteristics of power lifters, 5 competitive power lifters (PL; X +/- SE; age = 31.0 +/- 1.5 years, squat = 287.7 +/- 15.7 kg, bench press = 170.5 +/- 17.7 kg, and deadlift = 284.2 +/- 7.5 kg) and 5 untrained control subjects (CON; age = 27.3 +/- 3.3 years) served as subjects. Isokinetic squat force and power was greater (p0.05) for the PL at all bar velocities (0.20, 0.82, and 1.43 m;pd s(-1)), as was vertical jump height and estimated power. Muscle biopsies from the vastus lateralis m. revealed significant differences for percent fiber type (PL, IIA = 45.5 +/- 1.6%, IIB = 1.3 +/- 0.8%; CON, IIA = 33.4 +/- 3.1%, IIB = 12.0 +/- 2.4%); percent fiber type area (PL, IIA = 51.8 +/- 1.6%, IIB = 1.3 +/- 0.8%; CON, IIA = 43.5 +/- 3.4%, IIB = 12.4 +/- 2.6%); and percent myosin heavy chain isoform (PL, IIa = 59.5 +/- 6.1%; CON, 46.5 +/- 2.5%). Muscle fiber characteristics were significantly correlated (r = +/- 0.61) with numerous strength and power measures for the PL. These data illustrate the muscle fiber characteristics necessary for the maximal force production requirements of power lifting.

Bar trajectory during weightlifting movements is related to the position of the body during the lift and the displacement of the feet during the drop-under phase. The purpose of this study was to examine anterior-posterior foot displacement and its relationship with performance in the snatch of collegiate weightlifters. Snatch attempts of men weightlifters from the 1998 U.S.A. Weightlifting Collegiate National Championships were analyzed for horizontal displacement of the feet by video analysis. Lifts were analyzed under 2 conditions: all lifts combined and the heaviest successful attempt for each lifter. Lifts (n = 74) were placed into 4 groups: forward displacement (FD,2.5 cm); no displacement (ND, +/-2.5 cm); rearward displacement (RD,2.5 cm); and those that showed asymmetric (AS,7 cm difference in right and left foot) displacement of the feet. Chi-square revealed no significant difference in success rate between groups for all attempts. No statistically significant differences were noted between groups in body mass to bar mass ratio or Sinclair formula for heaviest successful attempts. Results indicate that foot displacement did not significantly affect snatch success or lifting ability in collegiate national level lifters.

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.

Currently, variables predictive of vertical jumping performance can account for only part of its total variability. A potential additional source of variation called explosive strength deficit (ESD) was described in 1995 by Zatsiorsky (Science and Practice of Strength Training. Champaign, IL: Human Kinetics, 1995. pp. 34-35.). ESD is determined by measuring the maximum force generated under ideal circumstances (F(mm)) and under task-relevant conditions (F(m)). It is calculated as 100(F(mm) - F(m))/F(m). For this study, the following operational definitions were used: F(mm) = squatting peak force at 0.51 m x s(-1); F(m) = squatting peak force at 1.43 m x s(-1). Data were analyzed using forward stepwise multiple regression. Mean ESD for men was 29.7% (SD = 11.7) and for women was 49.3% (SD = 11.2). For men and women, respectively, zero-order correlations for ESD with restricted vertical jumping (RVJ) distance were -0.35 and -0.60, and between ESD and drop vertical jumping (DVJ) distance were -0.20 and -0.63. However, when the previously identified predictors were taken into account, ESD was not a significant predictor (p0.05) of either type of jump. Therefore, it was concluded that ESD on the basis of velocity-regulated squats does not augment the explained variance previously established for vertical jumping performance.

The purpose of this study was to measure the effects of additional eccentric loading on subsequent concentric strength. Eight subjects with some experience in weight training volunteered to perform maximal attempts in the barbell bench press using detaching hooks that allowed them to lower 105% of their concentric 1 repetition maximum (RM) and raise 100%. The detaching hooks allowed attachment of extra weight to the bar and would release from the bar at the bottom of the lift, reducing the weight lifted during the concentric phase of the lift. After determining their 1RM for the bench press, the subjects attempted to increase their performance by using a heavier eccentric load with the detaching hooks. All 8 subjects who completed the study increased their 1RMs by 5 to 15 pounds. The use of additional eccentric loading significantly (p = 0.008) increased the weight that could be lifted on the subsequent concentric phase and therefore 1RM performance. This phenomenon was a result of the enhancement of stretch-shortening cycle performance by the increased eccentric load. Athletes who are interested in developing 1RM strength in the bench press may benefit from the use of additional eccentric loading.

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.

SCHILLING, B. K., M. H. STONE, A. UTTER, J. T. KEARNEY, M. JOHNSON, R. COGLIANESE, L. SMITH, H. S. O’BRYANT, A. C. FRY, M. STARKS, R. KEITH, and M. E. STONE. Creatine supplementation and health variables: a retrospective study. Med. Sci. Sports Exerc., Vol. 33, No. 2, 2001, pp. 183‐188. Purpose: Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate. Methods: Twenty-six athletes (18 M and 8 F, 24.7 6 9.2 y; 82.4 6 20.0 kg; 176.5 6 8.8 cm) from various sports were used as subjects. Blood was collected between 7:00 and 8:30 a.m. after a 12-h fast. Standard clinical examination was performed for CBC and 27 blood chemistries. Testosterone, cortisol, and growth hormone were analyzed using an ELISA. Subjects answered a questionnaire on dietary habits, creatine supplementation, medical history, training history, and perceived effects of supplementation. Body mass was measured using a medical scale, body composition was estimated using skinfolds, and resting heart rate and blood pressure were recorded. Subjects were grouped by supplementation length or no use: Gp1 (control) 5 no use (N 5 7; 3 F, 4 M); Gp2 5 0.8 ‐1.0 yr (N 5 9; 2 F, 7 M); and Gp3 5 1 1 (N 5 10; 3F , 7M ).Results: Creatine supplementation ranged from 0.8 ‐ 4 yr. Mean loading dose for Gp2 and Gp3 was 13.7 6 10.0 and the maintenance dose was 9.7 6 5.7 gzd -1 . Group differences were analyzed using one-way ANOVA. Conclusions: Expected gender differences were observed. Of the comparisons made among supplementation groups, only two differences for creatinine and total protein (P , 0.05) were noted. All group means fell within normal clinical ranges. There were no differences in the reported incidence of muscle injury, cramps, or other

Weight-trained men [OT ; n = 11; age = 22.0 ± 0.9 (SE) yr] resistance trained daily at 100% one-repetition maximum (1-RM) intensity for 2 wk, resulting in 1-RM strength decrements and in an overtrained state. A control group (Con; n = 6; age = 23.7 ± 2.4 yr) trained 1 day/wk at a low relative intensity (50% 1 RM). After 2 wk, the OT group exhibited slightly increased exercise-induced testosterone (preexercise = 26.5 ± 1.3 nmol/l, postexercise = 29.1 ± 5.9 nmol/l) and testosterone-to-cortisol ratio (preexercise = 0.049 ± 0.007 nmol/l, postexercise = 0.061 ± 0.006 nmol/l) and decreased exercise-induced cortisol (preexercise = 656.1 ± 98.1 nmol/l, postexercise = 503.1 ± 39.7 nmol/l). Serum concentrations for growth hormone and plasma peptide F [preproenkephalin (107—140)] were similar for both groups throughout the overtraining period. This hormonal profile is distinctly different from what has been previously reported for other types of overtraining, indicating that high-relative-intensity resistance exercise overtraining may not be successfully monitered via circulating testosterone and cortisol. Unlike overtraining conditions with endurance athletes, altered resting concentrations of pituitary, adrenal, or gonadal hormones were not evident, and exercise-induced concentrations were only modestly affected.

Mammalian skeletal muscle expresses at least two isoforms of the cytoskeletal protein titin (connectin; MW approximately 3000 kDa). These isoforms are associated with different passive force curves, and thus may affect physical performance. To study the distribution of titin and its possible influence on performance in humans, muscle biopsies were obtained from 15 males (mean +/- SE; age = 25.4 +/- 2.9 years, height = 177.7 +/- 1.8 cm, weight = 76.5 +/- 2.2 kg). Two biopsies were obtained on separate occasions from both the right and left vastus lateralis, and one biopsy each from the lateral head of the right gastrocnemius and the right soleus, with all biopsies handled identically. Fibre type analyses were performed via mATPase histochemistry. Expression of titin and myosin heavy chain isoforms were determined by SDS-PAGE. Titin bands in the resulting gels were highly repeatable and were verified by migration patterns, as well as Western blot analysis. Two groups of subjects were identified: group 1 (n = 10) expressed only one titin isoform (titin-1) in all biopsies, and group 2 (n = 5) expressed two titin isoforms (titin-1 and titin-2) in all biopsies. No significant differences (P > 0.05) between groups were observed for percentage fibre types, percentage fibre type areas, fibre type cross-sectional areas, and percentage myosin heavy chain expression when comparing individual muscles, sampling times or bilateral comparisons. This is the first report of differential titin isoform expression in healthy, mature human skeletal muscle, but it is not clear why this occurs or what influence this may have on performance.

Nine elite male junior weightlifters (mean age 17.6 ± 0.3 yrs) performed weightlifting tests before (Test 1) and after (Test 2) 1 week of increased training volume (overreaching) and repeated the protocol after 1 year of their training program. Strength increased by Year 2 (p

Eleven men sprint trained two to three times per week for 6 wk to investigate possible exercise-induced slow-to-fast fiber type conversions. Six individuals served as controls. Both groups were tested at the beginning and end of the study to determine anaerobic performance and maximal oxygen consumption. In addition, pre- and postbiopsies were extracted from the vastus lateralis muscle and were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain (MHC) content. No significant changes were found in anaerobic or aerobic performance variables for either group. Although a trend was found for a decrease in the percentage of type IIb fibers, high-intensity sprint cycle training caused no significant changes in the fiber type distribution or cross-sectional area. However, the training protocol did result in a significant decrease in MHC IIb with a concomitant increase in MHC IIa for the training men. These data appear to support previous investigations that have suggested exercise-induced adaptations within the fast fiber population (IIb-->IIa) after various types of training (endurance and strength).

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.

To examine endogenous anabolic hormonal responses to two different types of heavy resistance exercise protocols (HREPs), eight male and eight female subjects performed two randomly assigned protocols (i.e. P-1 and P-2) on separate days. Each protocol consisted of eight identically ordered exercises carefully designed to control for load, rest period length, and total work (J) effects. P-1 utilized a 5 RM load, 3-min rest periods and had lower total work than P-2. P-2 utilized a 10 RM load, 1-min rest periods and had a higher total work than P-1. Whole blood lactate and serum glucose, human growth hormone (hGH), testosterone (T), and somatomedin-C [SM-C] (i.e. insulin-like growth factor 1, IGF-1) were determined pre-exercise, mid-exercise (i.e. after 4 of the 8 exercises), and at 0, 5, 15, 30, and 60 min post-exercise. Males demonstrated significant (p less than 0.05) increases above rest in serum T values, and all serum concentrations were greater than corresponding female values. Growth hormone increases in both males and females following the P-2 HREP were significantly greater at all time points than corresponding P-1 values. Females exhibited significantly higher pre-exercise hGH levels compared to males. The P-1 exercise protocol did not result in any hGH increases in females. SM-C demonstrated random significant increases above rest in both males and females in response to both HREPs.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this study was to evaluate the effects of graded treadmill exercise on plasma preproenkephalin peptide F immunoreactivity and concomitant catecholamine responses at sea level (elevation, 50 m). Few data exist regarding the sea-level responses of plasma peptide F immunoreactivity to exercise. thirty-five healthy men performed a graded exercise test on a motor-driven treadmill at the relative exercise intensities of 25, 50, 75, and 100% of maximum oxygen consumption (VO2max). Significant (P less than 0.05) increases above rest were observed for plasma peptide F immunoreactivity and norepinephrine at 75 and 100% of the VO2 max and at 5 min into recovery. Significant increases in plasma epinephrine were observed at 75 and 100% of VO2max. Whole blood lactate significantly increased above resting values at 50, 75, and 100% of the VO2max and at 5 min into recovery. These data demonstrate that exercise stress increases plasma peptide F immunoreactivity levels at sea level. While the exercise response patterns of peptide F immunoreactivity are similar to catecholamines and blood lactate responses, no bivariate relationships were observed. These data show that sea-level response patterns to graded exercise are similar to those previously observed at moderate altitude (elevation, 2200 m).