The effect of aerobic exercise during the interset rest periods on kinematics, kinetics, and lactate clearance of two resistance loading schemes

It may be possible to enhance set and session kinematics and kinetics by engaging in low-intensity aerobic exercise during the interset rest period. The purpose of this study therefore was to quantify the change in session kinematics and kinetics of 35% 1RM and 70% 1RM loading schemes equated by volume, when aerobic exercise or passive rest was undertaken between sets. Twelve male student athletes were recruited for this study. Squat average force, peak force, average power, peak power, total work, and total impulse were quantified using a force plate and linear transducer. Blood lactate samples were taken before set 1, after set 1, after set 2, and after the last set performed. No significant (p < 0.05) differences (0.37-9.24%) were found in any of the kinematic and kinetic variables of interset after active or passive interset rest periods. Significant increases (64-76%) in blood lactate occurred from the inception of exercise to completion, for both the heavy and light loading schemes. However, no significant differences in lactate accumulation were noted, whether active or passive recovery was undertaken in the interest rest period. It was concluded that active recovery in the form of low-intensity cycling offered no additional benefits in terms of lactate clearance and enhancement of set and session kinematics and kinetics.     

The effects of training history, player position, and body composition on exercise performance in collegiate football players

Performance data for 261 NCAA Division 1A collegiate football players were analyzed to determine if player position, body weight, body fat, and training time were correlated with changes in performance in the following events: power clean (PC), bench press (BP), squat (SQ), vertical jump (VJ), 40-yd dash (40yd), and 20-yd shuttle (20yd). Individual positions were combined into the following groups: (A) wide receivers, defensive backs, and running backs, (B) linebackers, kickers, tight ends, quarterbacks, and specialists, and (C) linemen. Increases in body weight were positively correlated with increases in BP and PC performance for all groups. Increases in body fat were negatively correlated with performance in the PC and VJ for all groups. For group C, increases in body fat were also negatively correlated with performance in the 40yd and 20yd. Group and training time exhibited no linear relationship with performance in any of the tested events. No linear relationships were observed between the independent variables and performance in the SQ. When individual training data were analyzed longitudinally, a nonlinear increase in performance in the PC, BP, and SQ was observed as training time increased, with the greatest rate of change occurring between the first and second semesters of training.     

The acute effects of prior dynamic resistance exercise using different loads on subsequent upper-body explosive performance in resistance-trained men

The purpose of this study was to determine if explosive upper-body performance could be improved when it was preceded by conditioning contraction protocols that incorporate resistance exercise. Providing that performance was enhanced, it was also the intention to determine the optimal conditioning contraction load for enhancing performance. Eight recreationally trained men completed 4 experimental sessions. Each session consisted of a warm-up, 3 bench press throws (pre), a conditioning protocol, and 3 bench press throws (post). The different conditioning protocols consisted of 5 bench press repetitions using 100, 75, or 50% of 5 repetition maximum (5RM) strength. The fourth protocol, in which no repetitions were completed, acted as a control. Participants performed each conditioning protocol on a different day, and the order in which the protocols were performed was randomized. Average power, assessed during the bench press throws, was determined for the starting segment and the end segment (point of bar release) for each throw. Comparisons in average power, for each segment of the bench press 1RM, were made between the pre- and postconditioning protocol bench press throws. None of the conditioning protocols had an effect on bench press throw performance in either of the 2 segments of the movement. The results suggest there is no performance advantage when explosive upper-body movement is preceded by resistance exercise of varying loads. Alternatively, the performance of a set of resistance exercise did not compromise explosive upper-body performance. Considering this, training methods that combine both resistance exercise and plyometric-like exercise may offer a practical and time-efficient training system.     

The effect of rest interval length on multi and single-joint exercise performance and perceived exertion

The purpose of this study was to compare repetition performance and rating of perceived exertion (RPE) with 1-, 3-, or 5-minute rest intervals between sets of multi and single-joint resistance exercises. Fifteen resistance trained men (23.6 ± 2.64 years, 76.46 ± 7.53 kg, 177 ± 6.98 cm, bench press [BP] relative strength: 1.53 ± 0.25 kg·kg(-1) body mass) completed 12 sessions (4 exercises × 3 rest intervals), with each session involving 5 sets with 10 repetition maximum loads for the free weight BP, machine leg press (LP), machine chest fly (MCF), and machine leg extension (LE) exercises with 1-, 3-, 5-minute rest intervals between sets. The results indicated significantly greater BP repetitions with 3 or 5 minutes vs. 1 minute between sets (p ≤ 0.05); no significant difference was evident between the 3- and 5-minute rest conditions. For the other exercises (i.e., LP, MCF, and LE), significant differences were evident between all rest conditions (1 < 3 < 5; p ≤ 0.05). For all exercises, consistent declines in repetition performance (relative to the first set) were observed for all rest conditions, starting with the second set for the 1-minute condition and the third set for the 3- and 5-minute conditions. Furthermore, significant increases in RPE were evident over successive sets for both the multi and single-joint exercises, with significantly greater values for the 1-minute condition. In conclusion, both multi and single-joint exercises exhibited similar repetition performance patterns and RPE, independent of the rest interval length between sets.     

Effects of hypoxia on muscle protein synthesis and anabolic signaling at rest and in response to acute resistance exercise

Chronic reductions in tissue O(2) tension (hypoxia) are associated with muscle atrophy and blunted hypertrophic responses to resistance exercise (RE) training. However, the effect of hypoxia on muscle protein synthesis (MPS) at rest and after RE is unknown. In a crossover study, seven healthy men (21.4 ± 0.7 yr) performed unilateral leg RE (6 × 8 repetitions at 70% 1-repetition maximum) under normoxic (20.9% inspired O(2)) and normobaric hypoxic (12% inspired O(2) for 3.5 h) postabsorptive conditions. Immediately after RE the rested leg was biopsied, and a primed continuous infusion of [1,2-(13)C(2)]leucine was maintained for 2.5 h before final biopsies from both legs to measure tracer incorporation and signaling responses (i.e., ribosomal S6 kinase 1). After 3.5 h of hypoxia, MPS was not different from normoxia in the rested leg (normoxia 0.033 ± 0.016 vs. hypoxia 0.043 ± 0.016%/h). MPS increased significantly from baseline 2.5 h after RE in normoxia (0.033 ± 0.016 vs. 0.104 ± 0.038%/h) but not hypoxia (0.043 ± 0.016 vs. 0.060 ± 0.063%/h). A significant linear relationship existed between MPS 2.5 h after RE in hypoxia and mean arterial blood O(2) saturation during hypoxia (r(2) = 0.49, P = 0.04). Phosphorylation of p70S6K(Thr389) remained unchanged in hypoxia at rest but increased after RE in both normoxia and hypoxia (2.6 ± 1.2-fold and 3.4 ± 1.1-fold, respectively). Concentrations of the hypoxia-responsive mTOR inhibitor regulated in development and DNA damage-1 were unaltered by hypoxia or RE. We conclude that normobaric hypoxia does not reduce MPS over 3.5 h at rest but blunts the increased MPS response to acute RE to a degree dependent on extant SpO(2).     

The effects of rest interval length on acute bench press performance: the influence of gender and muscle strength

The purpose of this study was to investigate the effects of rest interval (RI) length on bench press performance in subjects with disparity in maximum strength. Two cohorts of subjects performed 3 bench press protocols in random order consisting of 3 sets of up to 10 repetitions with 75% of 1-repetition maximum (1RM) using either 1-, 2-, or 3-minute RIs between sets. In the first cohort, 22 men and women were studied to investigate gender influence. In the second cohort, 23 men were tested for 1RM bench press strength and placed into a low 1RM (mean = 80.7 ± 7.5 kg) or high 1RM (mean = 140.6 ± 11.9 kg) experimental group. The number of successful repetitions completed, average power, and velocity for each set were recorded. Women performed significantly more repetitions than men with 1-minute (26.9 ± 4.4 vs. 21.1 ± 3.5), 2-minute (29.0 ± 2.0 vs. 24.0 ± 4.5), and 3-minute (29.7 ± 1.8 vs. 25.8 ± 5.1) RIs. The magnitude of decline in average velocity and power was significantly higher in men than in women. Total number of repetitions performed was significantly greater in the low 1RM group than in the high 1RM group at 1-minute (21.6 ± 5.0 vs. 18.1 ± 2.0) and 2-minute RIs (24.2 ± 5.4 vs. 21.3 ± 2.8). Significant negative correlations were observed between 1RM bench press and total number of repetitions completed for 1- and 2-minute RIs (r = -0.558 and -0.490, respectively). These data indicate that maximal strength plays a role in bench press performance with varying RIs and suggest that shorter RIs may suffice in women to attain a specific volume.     

The effects of body position and exercise on plasma volume dynamics

We examined the plasma volume changes associated with a protocol of either exercise or controlled rest under identical positional and ambient conditions. Nine healthy adult males rode (E) and on another occasion sat quietly (C) on a cycle ergometer for 30 min. Ten minutes of cycle exercise immediately followed the resting C protocol. Ambient temperature was 30 degrees C (rh = 35%) and exercise load was equal to 50% of peak VO2. Venous blood samples were obtained with subjects both in the supine and seated positions prior to all experiments. Additional blood was drawn during minutes 1, 5, 10, and 30 in both experimental conditions. A final sample was taken during C after the 10 min exercise. Moving from the supine to a seated position resulted in an average loss of 162 ml of plasma across all experiments. During the E condition a further reduction in plasma volume (76 ml) occurred by one minute of exercise. Plasma volume stabilized by 5 min of exercise under the E protocol. During the C condition, subsequent fluid loss (98 ml) was not apparent until 10 min after the first seated sample and totalled 176 ml at the end of 30 min of rest. Ten minutes of cycling at the end of the C experiment resulted in a further plasma volume reduction of 137 ml. Plasma protein and albumin contents decreased by 5 min of exercise in E and by 30 min of rest in C. [Na+] and [Cl-] did not change in either condition but a rapid increase in [K+] during exercise indicated an addition of potassium to the vascular volume.(ABSTRACT TRUNCATED AT 250 WORDS)     

Training and detraining effects of the resistance vs. endurance program on body composition, body size, and physical performance in young men

The purpose of this study was to investigate the changes in the body composition, body size, muscle strength, and VO2max after 24 weeks of resistance or endurance training and detraining in young men. Thirty healthy college-aged men (20.4 ± 1.36 years) participated in the study. Subjects were assigned to resistance training group (RTG, n = 10), endurance training group (ETG, n = 10), and control group (CG, n = 10). The training program consisted of running or weight-resistance exercise for 3 sessions per week under supervision. VO2max, upper and lower body strength (UBS, LBS), body fat, lean body mass, and body circumference were measured at baseline and after training and detraining. After the training period, the exercise groups demonstrated significant increases in VO2max and LBS (p < 0.05). The UBS, lean mass (LM), and body size of arm and calf were significantly greater in the RTG than in the other 2 groups (p<0.05). In addition, the strength and LM of the RTG were still greater than the baseline values after 24 weeks of detraining (p < 0.05). The conclusions of this study are (a) that endurance or resistance training alone led to training-specific improvements in physical performance, body composition, and body size of the arms for the young men examined and (b) that the RTG maintained the gains in strength and LM for more prolonged periods after training ceased than the endurance training group.     

Effects of aerobic exercise on strength performance following various periods of recovery

The purpose of this study was to determine if the type and intensity of aerobic training affects performance in a subsequent strength-training session after varying periods of recovery. Sixteen male subjects participated in the study and were divided into 2 groups based on aerobic training, high-intensity intervals (MAX n = 8) and continuous submaximal (SUB n = 8). Each subject performed 4 sets of both bench press and leg press at approximately 75% 1 repetition maximum (1RM) following aerobic training with recovery periods of 4, 8, and 24 hours, as well as once in a control condition. Both the 4- and 8-hour conditions resulted in fewer total leg press repetitions than the control and 24-hour conditions. There was no difference between both the control and 24-hour conditions. No main effect was shown with respect to the type of aerobic training. It was concluded that when aerobic training precedes strength training, the volume of work that can be performed is diminished for up to 8 hours. This impairment appears to be localized to the muscle groups involved in the aerobic training.     

The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation and associated biochemical parameters in resistance trained men

Trepanowski, JF, Farney, TM, McCarthy, CG, Schilling, BK, Craig, SA, and Bloomer, RJ. The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation, and associated biochemical parameters in resistance trained men. J Strength Cond Res 25(12): 3461-3471, 2011-We examined the effects of chronic betaine supplementation on exercise performance and associated parameters in resistance trained men. Men were randomly assigned in a double-blind manner using a crossover design to consume betaine (2.5 g of betaine mixed in 500 ml of Gatorade?) or a placebo (500 ml of Gatorade?) for 14 days, with a 21-day washout period. Before and after each treatment period, tests of lower- and upper-body muscular power and isometric force were conducted, including a test of upper-body muscular endurance (10 sets of bench press exercise to failure). Muscle tissue oxygen saturation (StO2) during the bench press protocol was measured via near infrared spectroscopy. Blood samples were collected before and after the exercise test protocol for analysis of lactate, nitrate/nitrite (NOx), and malondialdehyde (MDA). When analyzed using a repeated measures analysis of variance, no significant differences were noted between conditions for exercise performance variables (p > 0.05). However, an increase in total repetitions (p = 0.01) and total volume load (p = 0.02) in the 10-set bench press protocol was noted with betaine supplementation (paired t-tests), with values increasing approximately 6.5% from preintervention to postintervention. Although not of statistical significance (p = 0.14), postexercise blood lactate increased to a lesser extent with betaine supplementation (210%) compared with placebo administration (270%). NOx was lower postintervention as compared with preintervention (p = 0.06), and MDA was relatively unchanged. The decrease in StO2 during the bench press protocol was greater with betaine vs. placebo (p = 0.01), possibly suggesting enhanced muscle oxygen consumption. These findings indicate that betaine supplementation results in a moderate increase in total repetitions and volume load in the bench press exercise, without favorably impacting other performance measures.     

Acute effects of static stretching and massage on flexibility and jumping performance

Objective:The purpose of this study was to evaluate the effects of static stretching and the application of massage on flexibility and jump performance.Methods:Thirty-five athletes studying Physical Education at University (mean age 23.6±1.3 years, mean height 177.8±6.3 cm and mean weight 72.2±6.7 kg) performed one of three different warm-up protocols on non-consecutive days. Protocols included static stretching [SS], combined static stretching and massage [SSM], and neither stretching nor massage [CONT]. The athletes performed flexibility, countermovement jump (CMJ) and squat jump (SJ) tests.Results:SS and SSM protocols demonstrated 12% (p<0.05) and 16% (p<0.05) respectively greater flexibility than the CONT protocol. SJ and CMJ performances were significantly decreased 10.4% (p<0.05) and 5.5% (p<0.05) respectively after the SS protocol. There was no significant difference between SSM and CONT protocol in terms of SJ and CMJ performance.Conclusion:This research indicates that whereas static stretching increases the flexibility it decreases the jumping performance of the athletes. On the other hand, the application of massage immediately following static stretching increases flexibility but does not reduce jumping performance. Considering the known negative acute effects of static stretching on performance, the application of massage is thought to be beneficial in alleviating such effects.     

The total cavopulmonary connection resistance: a significant impact on single ventricle hemodynamics at rest and exercise

Little is known about the impact of the total cavopulmonary connection (TCPC) on resting and exercise hemodynamics in a single ventricle (SV) circulation. The aim of this study was to elucidate this mechanism using a lumped parameter model of the SV circulation. Pulmonary vascular resistance (1.96+/-0.80 WU) and systemic vascular resistances (18.4+/-7.2 WU) were obtained from catheterization data on 40 patients with a TCPC. TCPC resistances (0.39+/-0.26 WU) were established using computational fluid dynamic simulations conducted on anatomically accurate three-dimensional models reconstructed from MRI (n=16). These parameters were used in a lumped parameter model of the SV circulation to investigate the impact of TCPC resistance on SV hemodynamics under resting and exercise conditions. A biventricular model was used for comparison. For a biventricular circulation, the cardiac output (CO) dependence on TCPC resistance was negligible (sensitivity=-0.064 l.min(-1).WU(-1)) but not for the SV circulation (sensitivity=-0.88 l.min(-1).WU(-1)). The capacity to increase CO with heart rate was also severely reduced for the SV. At a simulated heart rate of 150 beats/min, the SV patient with the highest resistance (1.08 WU) had a significantly lower increase in CO (20.5%) compared with the SV patient with the lowest resistance (50%) and normal circulation (119%). This was due to the increased afterload (+35%) and decreased preload (-12%) associated with the SV circulation. In conclusion, TCPC resistance has a significant impact on resting hemodynamics and the exercise capacity of patients with a SV physiology.     

The acute effects of combined static and dynamic stretch protocols on fifty-meter sprint performance in track-and-field athletes

The purpose of this study was to investigate the effect of manipulating the static and dynamic stretch components associated with a traditional track-and-field warm-up. Eighteen experienced sprinters were randomly assigned in a repeated-measures, within-subject design study with 3 interventions: active dynamic stretch (ADS), static passive stretch combined with ADS (SADS), and static dynamic stretch combined with ADS (DADS). A standardized 800-m jogged warm-up was performed before each different stretch intervention, followed by two 50-m sprints. Results indicated that the SADS intervention yielded significantly (p < or = 0.05) slower 50-m sprint times then either the ADS or DADS intervention. The decrease in sprint time observed after the ADS intervention compared to the DADS intervention was found to be nonsignificant (p > 0.05). The decrease in performance post-SADS intervention was attributed to a decrease in the musculotendinous unit (MTU) stiffness, possibly due to a reduction in muscle activation prior to ground contact, leading to a decrease in the MTU's ability to store and transfer elastic energy after the use of passive static stretch techniques. The improved 50-m sprint performance associated with the ADS and DADS interventions was linked to the rehearsal of specific movement patterns, helping proprioception and preactivation, allowing a more optimum switch from eccentric to concentric muscle contraction. It was concluded that passive static stretching in a warm-up decreases sprint performance, despite being combined with dynamic stretches, when compared to a solely dynamic stretch approach.     

The acute 1-week effects of the Zone diet on body composition, blood lipid levels, and performance in recreational endurance athletes

The aim of this study was to examine the effects of a 7-day Zone diet compared with a normal diet on maximal oxygen uptake (V(O)2 max), running time to exhaustion during endurance performance, and body composition. Eight men, with the following physical characteristics (mean +/- SE), participated in this study: age, 26.1 +/- 1.9 years; height, 178 +/- 1.7 cm; mass, 70.7 +/- 2.1 kg; and V(O)2 max, 54.6 +/- 3.1 ml x kg(-1) x min(-1). All subjects undertook pretesting for V(O)2 max, time to exhaustion (80% V(O)2 max), and body composition (Biostat 1500) before following either the normal diet or the Zone diet for 7 days. These performance trials were performed before and after the dietary period. There was a significant (p < 0.05) decrease in total energy consumption from a mean of 2,314 +/- 334 kcal on a pretest diet to 1,994 +/- 438 kcal on the Zone diet. Subjects showed a significant reduction (p < 0.02) in body mass from 70.7 +/- 2.1 kg to 69.8 +/- 2.1 kg. In the 80% V(O)2 max time to exhaustion trial, there was a significant reduction (p < 0.05) in time to exhaustion from 37.68 +/- 8.6 minutes for the pretest diet to 34.11 +/- 7.01 minutes for the Zone diet. In conclusion, the claim of the authors of the Zone diet that performance time and V(O)2 max can be improved was not shown in this 1-week research trial. We would suggest that this is not a nutritional strategy that athletes should use until further work has been conducted.