N. Travis Triplett

Acute Effects of Whole-Body Vibration on Muscle Activity, Strength, and Power

The purpose of this study was to investigate the effects of a single bout of whole-body vibration on isometric squat (IS) and countermovement jump (CMJ) performance. Nine moderately resistance-trained men were tested for peak force (PF) during the IS and jump height (JH) and peak power (PP) during the CMJ. Average integrated electromyography (IEMG) was measured from the vastus medialis, vastus lateralis, and biceps femoris muscles. Subjects performed the 2 treatment conditions, vibration or sham, in a randomized order. Subjects were tested for baseline performance variables in both the IS and CMJ, and were exposed to either a 30-second bout of whole-body vibration or sham intervention. Subjects were tested immediately following the vibration or sham treatment, as well as 5, 15, and 30 minutes posttreatment. Whole-body vibration resulted in a significantly higher (p ≤ 0.05) JH during the CMJ immediately following vibration, as compared with the sham condition. No significant differences were observed in CMJ PP; PF during IS or IEMG of the vastus medialis, vastus lateralis, or biceps femoris during the CMJ; or IS between vibration and sham treaments. Whole-body vibration may be a potential warm-up procedure for increasing vertical JH. Future research is warranted addressing the influence of various protocols of whole-body vibration (i.e., duration, amplitude, frequency) on athletic performance.

Quercetin's Influence On Exercise Performance And Muscle Mitochondrial Biogenesis

PURPOSE To determine the influence of 2 wk of quercetin (Q; 1000 mg x d(-1)) compared with placebo (P) supplementation on exercise performance and skeletal muscle mitochondrial biogenesis in untrained, young adult males (N = 26, age = 20.2 +/- 0.4 yr, VO2max = 46.3 +/- 1.2 mL x kg(-1) x min(-1)). METHODS Using a randomized, crossover design with a 2-wk washout period, subjects provided blood and muscle biopsy samples presupplementation and postsupplementation periods and were given 12-min time trials on 15% graded treadmills after 60 min of moderate exercise preloads at 60% VO2max. RESULTS Plasma Q levels rose significantly in Q versus P during the 2-wk supplementation period (interaction P value <0.001). During the 12-min trial, the net change in distance achieved was significantly greater during Q (2.9%) compared with P (-1.2%; 29.5 +/- 11.5 vs -11.9 +/- 16.0 m, respectively, P = 0.038). Skeletal muscle messenger RNA expression tended to increase (range = 16-25%) during Q versus P for sirtuin 1 (interaction effect, P = 0.152), peroxisome proliferator-activated receptor gamma coactivator-1alpha (P = 0.192), cytochrome c oxidase (P = 0.081), and citrate synthase (P = 0.166). Muscle mitochondrial DNA (relative copy number per diploid nuclear genome) increased 140 +/- 154 (4.1%) with Q compared with -225 +/- 157 (6.0% decrease) with P (P = 0.098). CONCLUSIONS In summary, 1000 mg x d(-1) Q versus P for 2 wk by untrained males was associated with a small but significant improvement in 12-min treadmill time trial performance and modest but insignificant increases in the relative copy number of mitochondrial DNA and messenger RNA levels of four genes related to mitochondrial biogenesis.

Relationship Between Maximal Squat Strength and Five, Ten, and Forty Yard Sprint Times

McBride, JM, Blow, D, Kirby, TJ, Haines, TL, Dayne AM, and Triplett, NT. Relationship between maximal squat strength and five, ten, and forty yard sprint times. J Strength Cond Res 23(6): 1633-1636, 2009-The purpose of this investigation was to examine the relationship between maximal squat strength and sprinting times. Seventeen Division I-AA male football athletes (height = 1.78 ± 0.04 m, body mass [BM] = 85.9 ± 8.8 kg, body mass index [BMI] = 27.0 ± 2.6 kg/m2, 1 repetition maximum [1RM] = 166.5 ± 34.1 kg, 1RM/BM = 1.94 ± 0.33) participated in this investigation. Height, weight, and squat strength (1RM) were assessed on day 1. Within 1 week, 5, 10, and 40 yard sprint times were assessed. Squats were performed to a 70° knee angle and values expressed relative to each subjects BM. Sprints were performed on a standard outdoor track surface with timing gates placed at the previously mentioned distances. Statistically significant (p ≤ 0.05) correlations were found between squat 1RM/BM and 40 yard sprint times (r = −0.605, p = 0.010, power = 0.747) and 10 yard sprint times (r = −0.544, p = 0.024, power = 0.626). The correlation approached significance between 5 yard sprint times and 1RM/BM (r = −0.4502, p = 0.0698, power = 0.4421). Subjects were then divided into those above 1RM/BM of 2.10 and below 1RM/BM of 1.90. Subjects with a 1RM/BM above 2.10 had statistically significantly lower sprint times at 10 and 40 yards in comparison with those subjects with a 1RM/BM ratio below 1.90. This investigation provides additional evidence of the possible importance of maximal squat strength relative to BM concerning sprinting capabilities in competitive athletes.

Effect of Pilates and taiji quan training on self-efficacy, sleep quality, mood, and physical performance of college students.

Methods of exercise such as Pilates and taiji quan, which have been shown to have beneficial effects on physical and mental characteristics, have been studied more often in samples of older participants. The purpose of this investigation was to examine the effects of a semester of either Pilates or taiji quan training on perceived self-efficacy, sleep quality and mood, as well as strength and balance in college-age individuals. Self-efficacy was found to be improved in the Pilates and taiji quan groups and there was a trend towards improvement in sleep quality. Mood was found to be improved significantly in the Pilates group while the taiji group showed a trend towards improvement. There were no changes or group differences in the strength or balance measures. Pilates and taiji quan are effective exercise modes to improve mental parameters in college-age individuals.

Effects of a short-term resistance program using elastic bands versus weight machines for sedentary middle-aged women.

Colado, JC and Triplett, NT. Effects of a short-term resistance program using elastic bands versus weight machines for sedentary middle-aged women. J Strength Cond Res 22(5): 1441-1448, 2008-This study was designed to determine whether different effects on functional capacity and body composition were produced by using different devices (elastic bands (EBs) versus weight machines (WMs)) with the same resistance training program. Forty-five healthy sedentary middle-aged women volunteers were chosen and randomly assigned to 1 of 3 groups: 21 subjects trained using EBs (EBG), 14 in trained using WMs (WMG), and 10 were controls (CG). Both exercise groups trained with a periodized muscular endurance program twice a week for 10 weeks, with a total of 6 exercises per session for the major muscle groups. Exercise intensity was equalized by jointly monitoring the same targeted number of repetitions (TNRs) and rate of perceived exertion in active muscles (RPE-AM). Functional capacity was assessed by using knee push-up (KPU) and 60-second squat (S) tests. Body composition was measured using an 8-polar bioelectrical impedance analyzer. The results for both the EBG and WMG show a decrease in fat mass (p = 0.05 and p < 0.01, respectively) and an increase in both the fat-free mass (p < 0.05 and p < 0.01, respectively) and the number of repetitions in the KPU (p < 0.05 and p < 0.01, respectively) and S tests (p < 0.01 in both). None of the variables measured for the CG varied significantly. It can be concluded that, independently of the device used, the combined monitoring of TNRs and RPE-AM can be a valid tool for controlling the resistance exercise intensity and can lead to healthy adaptations. EBs can thus offer significant physiological benefits that are comparable to those obtained from WMs in the early phase of strength training of sedentary middle-aged women.

Effect of an Acute Bout of Whole Body Vibration Exercise on Muscle Force Output and Motor Neuron Excitability

McBride, JM, Nuzzo, JL, Dayne, AM, Israetel, MA, Nieman, DC, and Triplett, NT. Effect of an acute bout of whole body vibration exercise on muscle force output and motor neuron excitability. J Strength Cond Res 24(1): 184-189, 2010-The purpose of the current investigation was to assess the effect of an acute bout of whole body vibration (WBV) exercise on muscle force output and motor neuron excitability. Nineteen recreationally trained college-aged males were randomly assigned to a WBV (n = 10) or a sham (S, n = 9) group. The WBV group completed a series of static, body weight squats on a vibrating platform at 30 Hz and an amplitude of ~3.5 mm (vertical), whereas the S group performed the same series of exercises but without vibration. Measurements were performed before (Pre) and then immediately post-exercise (Imm Post), 8 minutes post-exercise (8-Min Post), or 16 minutes post-exercise (16-Min Post) during 3 different testing sessions. The measurements involved a ballistic isometric maximum voluntary contraction (MVC) of the triceps surae muscle complex and electrical stimulation of the tibial nerve for assessment of motor neuron excitability by analyzing H-reflex and M-wave responses (Hmax/Mmax ratio). Electromyography was also obtained from the triceps surae muscle complex during the MVCs. The WBV group significantly (p ≤ 0.05) increased peak force at Imm Post (9.4%) and 8-Min Post (10.4%). No significant change in peak force was observed in the S group. No significant changes were observed in either group for average integrated EMG, Hmax/Mmax ratio, or rate of force development at Imm Post, 8-Min Post, or 16-Min Post. The results from this investigation indicate that an acute bout of static, body weight squat exercises, combined with WBV, increases muscle force output up to 8 minutes post-exercise. However, this increase in muscle force is not accompanied by a significant increase in motor neuron excitability or muscle activation. Thus, it is plausible to use WBV as a method for acute increase in muscle force output for athletes immediately before competition.

The effect of resistance exercise on humoral markers of oxidative stress.

UNLABELLED Previous research attempts to identify an oxidative stress response to acute resistance exercise have yielded mixed results. Inconsistencies in the current literature base probably reflect study-to-study variance in resistance exercise protocols; where high volume and short recovery elicit the most identifiable oxidative stress response. PURPOSE This study examined the effect of resistance exercise intensity on blood oxidative stress. METHODS To elicit a blood oxidative stress, 10 subjects undertook two different back squat protocols: 1) a hypertrophy protocol of four sets, 10 repetitions with 90 s of rest at 75% one-repetition max (1RM); and 2) a strength protocol of 11 sets, three repetitions with 5 min of rest at 90% 1RM. The resistance exercise protocols were standardized for total volume and completed in a randomized crossover fashion with 1 wk between trials. Blood drawn before (PRE), immediately following exercise (IP), and 60 min following exercise (60POST) was analyzed for markers of oxidative stress and damage. RESULTS In response to both hypertrophy and strength exercise protein carbonyls were significantly elevated IP and 60POST while plasma lipid hydroperoxides were not. Following the hypertrophy protocol, trolox equivalent antioxidant capacity was elevated IP while urate lower than baseline. At the 60POST time point plasma ferric reducing ability of plasma was elevated following the hypertrophy protocol. Based on protein carbonyl data, a similar oxidative stress was incurred following both hypertrophy and strength protocols. CONCLUSION Normalization for time of blood draw following the two protocols indicates that the magnitude of blood oxidative protein damage was identical between the protocols. These findings demonstrate that both resistance exercise protocols elicited a blood oxidative stress in a time-dependent fashion.

Comparison of Methods to Quantify Volume During Resistance Exercise

McBride, JM, McCaulley, GO, Cormie, P, Nuzzo, JL, Cavill, MJ, and Triplett, NT. Comparison of methods to quantify volume during resistance exercise. J Strength Cond Res 23(1): 106-110, 2009-The purpose of this investigation was to compare 4 different methods of calculating volume when comparing resistance exercise protocols of varying intensities. Ten Appalachian State University students experienced in resistance exercise completed 3 different resistance exercise protocols on different days using a randomized, crossover design, with 1 week of rest between each protocol. The protocols included 1) hypertrophy: 4 sets of 10 repetitions in the squat at 75% of a 1-repetition maximum (1RM) (90-second rest periods); 2) strength: 11 sets of 3 repetitions at 90% 1RM (5-minute rest periods); and 3) power: 8 sets of 6 repetitions of jump squats at 0% 1RM (3-minute rest periods). The volume of resistance exercise completed during each protocol was determined with 4 different methods: 1) volume load (VL) (repetitions [no.] × external load [kg]); 2) maximum dynamic strength volume load (MDSVL) (repetitions [no.] × [body mass − shank mass (kg) + external load (kg)]); 3) time under tension (TUT) (eccentric time +milliseconds] + concentric time +milliseconds]); and 4) total work (TW) (force [N] × displacement [m]). The volumes differed significantly (p < 0.05) between hypertrophy and strength in comparison with the power protocol when VL and MDSVL were used to determine the volume of resistance exercise completed. Furthermore, significant differences in TUT existed between all 3 resistance exercise protocols. The TW calculated was not significantly different between the 3 protocols. These data imply that each method examined results in substantially different values when comparing various resistance exercise protocols involving different levels of intensity.

Concentric and Impact Forces of Single-Leg Jumps in an Aquatic Environment versus on Land

PURPOSE This study investigated the kinetic and the kinematic differences in female athletes in single-leg static jumps in an aquatic environment compared with those performed on dry land. METHODS Twelve healthy, junior national team handball players participated. Subjects completed a familiarization and a testing session. The subjects performed a series of single-leg jumps, dry land and aquatic with and without devices, which were randomized to avoid fatigue effects. Peak concentric force, rate of force development, impact force, and time of the jumps were determined using a force plate. RESULTS Peak concentric force and rate of force development were significantly (P < 0.05) higher in the aquatic jumps, whereas impact force was significantly (P < 0.05) lower. There was a shorter total jump time (P < 0.05) for the aquatic jump without devices, whereas the time required to reach peak force was not significantly different between the two environments, despite the greater resistance to movement in the aquatic medium. DISCUSSION Aquatic jump exercises result in greater force production and rate of force development in the same amount of time with less impact and can thus offer a viable alternative to traditional dry-land jump exercises, which may also be beneficial for rehabilitating or aging populations. The benefits of this type of exercise include an exercise mode that can be performed without compromising speed while reducing the potential for joint injury.

Testing of the maximal dynamic output hypothesis in trained and untrained subjects.

Nuzzo, JL, McBride, JM, Dayne, AM, Israetel, MA, Dumke, CL, and Triplett, NT. Testing of the maximal dynamic output hypothesis in trained and untrained subjects. J Strength Cond Res 24(5): 1269-1276, 2010-The maximal dynamic output (MDO) hypothesis is a newly proposed concept, which suggests that the muscular system of the lower limbs is designed to produce maximal power output when performing countermovement vertical jumping (CMJ) at body mass as opposed to other loading conditions. However, it is unclear if the MDO concept can be applied to individuals with different levels of maximal strength. The purpose of this investigation was to determine if subjects, who have distinct differences in maximal strength, maximize CMJ power at body mass. Fourteen male strength-power trained subjects (squat 1 repetition maximum (1RM)-to-body mass ratio = 1.96 ± 0.24) and 6 untrained male subjects (squat 1RM-to-body mass ratio = 0.94 ± 0.18) completed CMJs with loads that were less than, equal to, and greater than body mass. Loads less than body mass were accomplished with a custom-designed unloading apparatus, and loads greater than body mass were accomplished with a barbell and weights. In both groups, mean values for CMJ peak and mean power were greatest during the body mass jump. Power outputs at body mass were significantly different (p ≤ 0.05) than power outputs at various conditions of loading and unloading. These data support the MDO hypothesis and its application to individuals with significantly different 1RM-to-body mass ratios. Additionally, these data further support the idea that body mass CMJs are a theoretically sound way to train for power because of the maximal power outputs that are produced during this condition.