Efficacy of instability resistance training.

The use of the stability ball as a platform for upper-body resistance training has gained much attention in recent years. However, the efficacy of such training regimens remains largely unstudied. The purpose of this study was to evaluate the influence of platform (unstable vs. stable, stability ball vs. flat bench) on strength and work capacity during barbell chest-press exercise. We also sought to determine the effects of a barbell chest-press training program performed on a stability ball or flat bench on strength, work capacity, and abdominal power. Fourteen young women (20 - 23 yr) performed a 1 repetition maximum (1RM) barbell chest-press and the YMCA bench press test (YBT) on a stability ball and flat bench, as well as two field tests measuring abdominal power. The women were then assigned to perform 3 weeks of barbell chest-press training on a stability ball (SB group) or flat bench (FB group); assignment was balanced based on 1RM strength. Barbell chest-press training included 3 sets of 3 - 5 repetitions at loads greater or equal to 85 % of 1RM. The 1RM barbell chest-press, YBT, front abdominal power test (FAPT), and side abdominal power test (SAPT) were used to evaluate changes in strength, work capacity, and abdominal power, respectively. The chest-press tests were completed on both platforms following the training program. Platform (stability ball vs. flat bench) had no influence on strength, but work capacity was initially 12 % lower on the stability ball compared to the flat bench. In response to training, both groups significantly increased strength and work capacity, and there were no group differences. The increase in 1RM strength was 15 % and 16 % on the stability ball and flat bench for the SB group, and 16 % and 19 % for the FB group, respectively. The increase in work capacity was 32 % and 13 % on the stability ball and flat bench for the SB group, and 27 % and 26 % for the FB group, respectively. Both groups significantly improved on the FAPT, and there were no group differences. Performance on the FAPT improved by 5 % for the SB group, and 22 % for the FB group. Performance on the SAPT did not change. Barbell chest-press training performed on either the stability ball or flat bench increased strength and work capacity, and these changes were transferable across platforms. Thus, the stability ball is an effective platform for barbell chest-press training in untrained women over a short duration.

The effects of massage on delayed onset muscle soreness.

OBJECTIVES: The purpose of this study was to investigate the physiological and psychological effects of massage on delayed onset muscle soreness (DOMS). METHODS: Eighteen volunteers were randomly assigned to either a massage or control group. DOMS was induced with six sets of eight maximal eccentric contractions of the right hamstring, which were followed 2 h later by 20 min of massage or sham massage (control). Peak torque and mood were assessed at 2, 6, 24, and 48 h postexercise. Range of motion (ROM) and intensity and unpleasantness of soreness were assessed at 6, 24, and 48 h postexercise. Neutrophil count was assessed at 6 and 24 h postexercise. RESULTS: A two factor ANOVA (treatment v time) with repeated measures on the second factor showed no significant treatment differences for peak torque, ROM, neutrophils, unpleasantness of soreness, and mood (p > 0.05). The intensity of soreness, however, was significantly lower in the massage group relative to the control group at 48 h postexercise (p < 0.05). CONCLUSIONS: Massage administered 2 h after exercise induced muscle injury did not improve hamstring function but did reduce the intensity of soreness 48 h after muscle insult.

Effects of meal form and composition on plasma testosterone, cortisol, and insulin following resistance exercise.

The purpose of this study was to examine the effects of postexercise feeding on plasma levels of insulin, testosterone, cortisol, and testosterone:cortisol (T:C). Ten experienced, resistance trained males (20.7 +/- 0.95 years) were given whole food (WF: protein 38 g; carbohydrate 70 g; fat 7 g), a supplemental drink (SD; isocaloric and isonitrogenous to WF), an isocaloric carbohydrate beverage (C), or a placebo beverage (P) immediately, 2 and 4 hours after a standardized weight training protocol on 4 days, each separated by 1 week, in a repeated measures design. Subjects also received a standardized meal at 7 and 12 hours postexercise. Insulin, testosterone, and cortisol were measured pre-exercise and during 24 hours of recovery (at 0.5, 2.5, 4.5, 8, and 24 hours) using venous blood samples. Significant (condition 3 time) interactions were found for insulin, testosterone, and T:C, but not for cortisol (p <. 05). The SD yielded a greater response for insulin than all other conditions. Conversely, P demonstrated the greatest values for testosterone and T:C at 2.5 and 4.5 hours postexercise. Cortisol did not vary between conditions and there were no condition effects for insulin, testosterone, cortisol, and T:C at 8 or 24 hours. In conclusion, the efficacy of postexercise feeding for optimizing T:C and muscle growth is unclear; however, consumption of SD appears to maximize circulating insulin for several hours following resistance exercise.

Impact of rapid weight loss on cognitive function in collegiate wrestlers.

PURPOSE: The purpose of this study was to examine the effects of rapid weight loss (RWL) on cognitive function in collegiate wrestlers. METHODS: Wrestlers (N = 14) and controls (N = 15) were college-aged males who were tested at three different times: baseline, RWL, and rehydration. Wrestlers practiced RWL in preparation for competition while controls maintained normal body weight and dietary practices throughout the study. At each test session, blood glucose, hemoglobin (Hgb), hematocrit (Hct), plasma volume (PV), and body weight were measured. Subjects also completed mood and hypoglycemic profiles as well as five short cognitive tests. RESULTS: Two-way ANOVA and post-hoc tests revealed poorer performance for wrestlers than controls in two recall tests as well as greater mood negativity for the wrestlers after RWL. With RWL, between group differences were also evident in hypoglycemic profile, blood glucose, PV, and body weight. All measures returned to near baseline values after rehydration, suggesting that all physiological and cognitive effects associated with RWL were reversible. It is possible that precompetition anxiety may partially explain the results. CONCLUSIONS: RWL in collegiate wrestlers before a competition appears to cause physiological effects that are accompanied by transient mood reduction and impairment of short-term memory. The potential negative impact of this practice on the student-athlete should be considered.

Resilience to exercise detraining in healthy older adults.

OBJECTIVE: To determine the effects of stopping and restarting two types of exercise programs in older adults. DESIGN: A controlled, longitudinal study that utilized random assignment of volunteers. Treatments were exercise programs designed to improve cardiovascular or neuromuscular fitness. MEASUREMENTS: Dependent variables measured before and after implementation of treatments were: maximum oxygen consumption, oxygen pulse, treadmill and cycle training workloads, quadriceps isokinetic peak torque, quadriceps isokinetic total work, and quadriceps training workload. MAIN RESULTS: Exercise training was highly effective in improving cardiovascular endurance or muscular strength. Ten weeks of exercise detraining resulted in small losses in newly gained cardiovascular capacity but more noticeable losses in muscular strength. Exercise retraining was accomplished easily using cardiovascular or resistive exercises. The functional benefits of restarting a cardiovascular exercise program appeared additive despite a 10-week intervening period of exercise detraining. In this age group, cardiovascular exercise produced limited improvements in muscular strength, and resistive exercise training positively influenced cardiovascular exercise performance. CONCLUSIONS: Older adults are fairly resilient to 10 weeks of cardiovascular detraining and retain newly gained muscular strength for at least 5 weeks, despite an interruption of formal exercise. An occasional missed exercise session or temporary cessation of habitual exercise should not be a cause for distress in exercising older adults. Instead, they should realize the case with which they may restart their exercise program and also appreciate the generalized fitness benefits that can be ascribed to becoming more active.

Exercise intensity and the thermic effect of food.

This study investigated the effect of varying exercise intensity on the thermic effect of food (TEF). Sixteen lean male subjects were matched for VO2 max and randomly assigned to either a high or low intensity group for 30 min of treadmill exercise. Caloric expenditure was measured using indirect calorimetry at rest and at 30-min intervals over 3 hrs following each of three conditions: a 750-kcal liquid meal, high or low intensity exercise, and a 750-kcal liquid meal followed by high or low intensity exercise. Low intensity exercise enhanced the TEF during recovery at 60 and 90 min while high intensity enhanced it only at 180 min but depressed it at 30 min. Total metabolic expense for a 3-hr postmeal period was not differently affected by the two exercise intensities. Exercise following a meal had a synergistic effect on metabolism; however, this effect was delayed until 180 min postmeal when exercise intensity was high. The circulatory demands of high intensity exercise may have initially blunted the TEF, but ultimately the TEF measured over the 3-hr period was at least equal to that experienced following low intensity exercise.

Effect of breathing instruction on blood pressure responses during isometric exercise.

Twenty-seven normotensive, college-aged, female subjects were studied to assess the effects of training in breathing techniques on blood pressure during isometric contractions. Subjects were randomly and equally assigned to one of three training groups: 1) a group that was taught to perform a Valsalva maneuver during isometric efforts (VAL Group), 2) a group that was instructed to avoid performing the Valsalva maneuver (NO-VAL Group), and 3) a control group that was given no instructions (CONT Group). Prior to and following three breathing technique training sessions, two blood pressure measurements were made by amplified auscultation during 10 isometric contractions of the quadriceps femoris muscle with the leg positioned at 65 degrees of knee flexion. Breathing patterns were recorded on an impedance pneumograph. Data were submitted to a 2 X 2 X 3 (time X trial X group) multivariate analysis of covariance using resting systolic and diastolic blood pressures as covariates. A significant (p less than .05) time-x-group interaction revealed posttraining blood pressure response to isometric exercise had significantly decreased in the NO-VAL Group (163/120 vs 148/112 mm Hg), and had not significantly changed in the CONT Group (157/117 vs 153/117 mm Hg). These data illustrate that training to avoid the Valsalva maneuver may help attenuate the pressor response observed during isometric contractions and provide a means for safer patient exercise.

The effect of prophylactic knee bracing on performance.

This study examined the effect of prophylactic knee bracing upon performance in 35 college-aged athletes. Twenty-five male and ten female subjects completed two sets of tests to determine quadriceps peak torque, rise time, time to fatigue, anaerobic power, and blood lactate accumulation. On one trial the subjects wore a Stromgren dual-hinged prophylactic knee brace. MANOVA analysis revealed that bracing did not significantly affect the performance of football players (males) but did inhibit the overall performance of lacrosse players (females) (P less than 0.05). Post hoc analyses determined that rise time (time to develop peak torque) was the greatest contributor among the dependent variables to the multivariate difference observed in the females. However, no isolated variable was identified as significantly different between the conditions by repeated-measures t-tests. Additional analyses disclosed that familiarity with brace wearing, order of testing, or a trial effect (i.e., learning) did not alter the performance results. It was concluded that wearing a protective knee brace does not improve performance and may inhibit performance in some asymptomatic athletes. It is suggested that athletes and coaches reexamine the use of prophylactic braces based upon these findings and other research described in this paper.

Opioids and exercise. An update.

A number of endogenously produced opioid peptides interact with centrally and peripherally located specific receptors to form a widespread neuroendocrine system with many implications for human function. It is becoming increasingly evident that moderately high and high intensity exercise stimulate the release of the opioid peptide beta-endorphin to the circulation and this event may be subject to considerable intra- and interindividual variation. Moreover, endorphin levels probably remain elevated for 15 to 60 minutes following exercise. The duration of exertion does not seem to be critical, and low or moderate (less than 75% VO2max) intensity efforts do not stimulate this response. It also appears (mostly from animal model research) that exercise might elicit central opioid effects, but there is conflicting evidence on this topic. Physical training may encourage adapted opioid system function (e.g. altered peptide response to exercise or receptor number), but these adaptations are not well elucidated by the few existing studies. The significance of peripherally released opioid peptides during exercise has frequently been questioned. Exercise-induced affective response (e.g. mood enhancement), analgesia, food intake suppression and reproductive dysfunction are often mentioned as potentially controlled by an opioid mediated mechanism. While most of these events are normally considered under central control, it is time we begin entertaining the notion of peripheral effects (e.g. altered catecholamine release) and afferent input affecting central function in some of these phenomena. Additionally, evidence exists to suggest peripherally released enkephalins may cross the blood-brain barrier, but this is probably not true for endorphins. A number of other reported exercise-related events could possibly involve an underlying opioid mechanism. Exercise-associated metabolic regulation, immunosuppression, and cardiovascular function are areas for future opioid research.

Serum beta-endorphin and affective responses to graded exercise in young and elderly men.

Nine young (26.1 +/- 2.52 years) (M +/- SD) and seven elderly (66.0 +/- 5.85 years) untrained men performed a graded exercise to peak VO2 to compare whether serum beta-endorphin (B-EP) would respond similarly with age. B-EP levels were not different at rest (31.8 +/- 3.3 and 25.3 +/- 4.1 pg/ml in the old and young groups, respectively), and both groups displayed similar responses to exercise. Specifically, we noted no change in B-EP during the final stage of exercise followed by a significant rise for the recovery period (40.0 +/- 3.7 and 38.1 +/- 5.0 pg/ml in the aged and young groups, respectively). Post-exercise reports of anxiety and depression were unchanged in either group, and only minor changes in hostility were noted, as measured by the Multiple Affect Adjective Checklist. These results demonstrate a similar serum B-EP response in older men compared to young men following graded maximal exercise and support the contention that circulatory changes in B-EP may not be related to changes in specific affective states.

Serum beta-endorphin levels during a graded exercise test to exhaustion.

Serum beta-endorphin levels during a graded exercise test to exhaustion. Med. Sci. Sports Exerc., Vol. 19, No. 2, pp. 78-82, 1987. Nine untrained college age males completed a graded exercise protocol to maximal capacity on a bicycle ergometer to determine if there was a relationship between intensity of exercise and serum beta-endorphin (beta-EP) levels. Subjects fasted for 12 h and abstained from physical activity at least 24 h prior to testing. Subjects completed the Multiple Affect Adjective Check List prior to and following exercise to ascertain if psychological state would be associated with beta-EP levels. The initial workload was 150 kilopond meters and was increased 150 kilopond meters every 3 min until VO2max or leg fatigue occurred. Expired gases were continuously analyzed, and a venous blood sample was drawn from an indwelling catheter during the final 30 s of each stage and 5-min post-exercise. beta-EP levels were determined from serum using a radioimmunoassay technique and corrected for cross-reactivity with beta-lipotropin using affinity chromatography. Resting beta-EP levels were 25.3 +/- 4.1 pg X ml-1 and did not demonstrate significant changes during any stage of exercise. A correlation analysis (r = 0.30) revealed no significant relationship between exercise intensity and beta-EP levels. Following exercise, beta-EP levels were significantly increased compared to resting values (38.8 +/- 4.8 pg X ml-1). In addition, psychological state was unaffected by exercise despite significant increases in recovery beta-EP levels.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo opioid receptor occupation in the rat brain following exercise.

The effects of prolonged swim-stress (2 h and 1 h) upon brain opioid receptor binding of tritiated [3H]diprenorphine were investigated in male Sprague-Dawley rats. This was accomplished by injecting the label intravenously immediately following the swim, then allowing 20 min for tracer washout from non-specific binding sites, sacrificing the animal, dissecting the brain into several discrete areas (medulla-pons, mid-brain, mesolimbic, caudate, thalamus, and hypothalamus), and subsequently preparing homogenates from each brain area. Data were obtained from scintillation counting of the homogenates. A separate support experiment measured circulating beta-endorphin endorphin like immunoreactivity immediately following 2 h of swim-stress. Blood-borne beta-endorphin levels were significantly enhanced by the swim. Additionally, [3H]diprenorphine binding was insignificantly elevated following the 1-h swim and significantly greater in 5 of 6 brain areas examined subsequent to the 2-h swim. Greater availability of opioid receptors to allow enhanced binding of [3H]diprenorphine may have been caused by decreased competition for available receptors from endogenously produced peptides or possibly by alterations in receptor-binding characteristics. These proposed explanations await further investigation. As a result of these studies, we conclude: exercise-induced enhancement of peripheral beta-endorphin probably does not have a supraspinal action; and prolonged swim-stress apparently alters opioid receptor occupancy in the rat brain, and this effect may be dependent upon exercise duration.

In vivo autoradiography: visualization of stress-induced changes in opiate receptor occupancy in the rat brain.

A method of in vivo autoradiography was utilized which allows the visualization of local changes in opiate receptor occupation in the intact rat brain. The method is based on the exclusion of [3H]diprenorphine binding in areas in which the release of endogenous opiate peptides is increased by behavioral manipulation. The technique lends itself to the use of film autoradiography, allowing the mapping of relative levels of functional receptor occupancy throughout the whole brain. Prolonged intermittent footshock and forced swims in cold water (two stress-inducing manipulations which are known to release endogenous opiates) were found to cause highly significant decreases in specific high-affinity [3H]diprenorphine binding, as measured by liquid scintillation counting. These changes were unaccompanied by corresponding changes in non-specific binding and were not related to local changes in blood flow. A prolonged non-stressful swim in warm water caused no changes in [3H]diprenorphine binding. The use of tritium-sensitive film autoradiography allowed the resolution of these decreases to the level of individual nuclei. Differences in specific binding were found to be greatest in the periaqueductal gray, the reticular formation, and in midline-intralaminar thalamic nuclei, all of which have been implicated in the modulation of pain sensation.