Chad A. Witmer

An Investigation Into the Relationship of Flexibility, Power, and Strength to Club Head Speed in Male Golfers

Gordon, BS, Moir, GL, Davis, SE, Witmer, CA, and Cummings, DM. An investigation into the relationship of flexibility, power, and strength to club head speed in male golfers. J Strength Cond Res 23(5): 1606-1610, 2009-The purpose of this study was to investigate the relationship of flexibility, power, and strength to club head speed (CHS) in male golfers. Fifteen golfers (mean age ± SD: 34.3 ± 13.6 years) with a handicap of ≤8 volunteered for the study. Following a standardized warm-up, subjects proceeded to hit 5 wiffle golf balls with a 5 iron while their CHS was measured. Rotational trunk flexibility was measured on a trunk rotator machine. An index of total body rotational power was measured through a hip toss with a 3-kg medicine ball while an 8-repetition maximum (RM) on a pec deck machine was used to measure chest strength. Pearson correlations were used to assess the magnitude of the relationships between CHS and the measures of flexibility, power, and strength. Partial correlations were then run to assess the effect of handicap on the observed relationships. The only variables that were significantly correlated to CHS were chest strength (r = 0.69, p < 0.05) and total body rotational power (r = 0.54, p < 0.05). These relationships were unchanged when the effect of handicap was controlled for. The results of this study show that strength of the chest in the pec deck motion and total body rotational power significantly correlate with CHS in male golfers. This information can be used by practitioners to develop training programs and field tests for golfers.

Familiarization, Reliability, and Evaluation of a Multiple Sprint Running Test Using Self-Selected Recovery Periods

Glaister, M, Witmer, C, Clarke, DW, Guers, JJ, Heller, JL, and Moir, GL. Familiarization, reliability, and evaluation of a multiple sprint running test using self-selected recovery periods. J Strength Cond Res 24(12): 3296-3301, 2010-The aims of the present study were to investigate the process of self-selected recovery in a multiple sprint test with a view to using self-selected recovery time as a means of reliably quantifying an individuals ability to resist fatigue in this type of exercise. Twenty physically active exercise science students (means ± SD for age, height, body mass, body fat, and &OV0312;O2max of the subjects were 21 ± 2 yr, 1.79 ± 0.09 m, 83.7 ± 10.8 kg, 16.6 ± 3.9%, and 52.7 ± 7.2 ml·kg−1·min−1, respectively) completed 4 trials of a 12 × 30 m multiple sprint running test under the instruction that they should allow sufficient recovery time between sprints to enable maximal sprint performance to be maintained throughout each trial. Mean recovery times across the 4 trials were 73.9 ± 24.7, 82.3 ± 23.8, 77.6 ± 19.1, and 77.5 ± 13.9 seconds, respectively, with variability across the first 3 trials considered evidence of learning effects. Test-retest reliability across trials 3 to 4 revealed a good level of reliability as evidenced by a coefficient of variation of 11.1% (95% likely range: 8.0-18.1%) and an intraclass correlation coefficient of 0.76 (95% likely range: 0.40-0.91). Despite no change in sprint performance throughout the trials, ratings of perceived exertion increased progressively and significantly (p < 0.001) from a value of 10 ± 2 after sprint 3 to 14 ± 2 after sprint 12. The correlation between relative &OV0312;O2max and mean recovery time was 0.14 (95% likely range: −0.37-0.58). The results of the present study show that after the completion of 2 familiarization trials, the ability to maintain sprinting performance in a series of repeated sprints can be self-regulated by an athlete to a high degree of accuracy without the need for external timepieces.

The effects of load on system and lower-body joint kinetics during jump squats

To investigate the effects of different loads on system and lower-body kinetics during jump squats, 12 resistance-trained men performed jumps under different loading conditions: 0%, 12%, 27%, 42%, 56%, 71%, and 85% of 1-repetition maximum (1-RM). System power output was calculated as the product of the vertical component of the ground reaction force and the vertical velocity of the bar during its ascent. Joint power output was calculated during bar ascent for the hip, knee, and ankle joints, and was also summed across the joints. System power output and joint power at knee and ankle joints were maximized at 0% 1-RM (p < 0.001) and followed the linear trends (p < 0.001) caused by power output decreasing as the load increased. Power output at the hip was maximized at 42% 1-RM (p = 0.016) and followed a quadratic trend (p = 0.030). Summed joint power could be predicted from system power (p < 0.05), while system power could predict power at the knee and ankle joints under some of the loading conditions. Power at the hip could not be predicted from system power. System power during loaded jumps reflects the power at the knee and ankle, while power at the hip does not correspond to system power.

The acute effects of manipulating volume and load of back squats on countermovement vertical jump performance.

Moir, GL, Mergy, D, Witmer, CA, and Davis, SE. The acute effects of manipulating volume and load of back squats on countermovement vertical jump performance. J Strength Cond Res 25(6): 1486-1491, 2011—The acute effects of manipulating the volume and load of back squats on subsequent countermovement vertical jump performance were investigated in the present study. Eleven National Collegiate Athletic Association division II female volleyball players performed 10 countermovement vertical jumps (CMJs) on a force platform 2 minutes after the last squat repetition of a high-load (HL) or high-volume (HV) squat protocol. Two minutes of rest was provided between each CMJ. The HL protocol culminated in the subjects having to perform 3 repetitions with a load equivalent to 90% 1 repetition maximum (1RM) back squat, whereas 12 repetitions with a load equivalent to 37% 1RM were performed in the HV protocol. During an initial familiarization session, knee angles were recorded during a series of CMJs, and these angles were used to control the depth of descent during all subsequent back squats. Jump height (JH) and vertical stiffness (VStiff) were calculated during each of the 10 CMJ, and the change in these variables after the 2 squat protocols was assessed using an analysis of variance model with repeated measures on 2 factors (Protocol [2-levels]; Time [2-levels]). There was no significant difference in JH after the HL and HV protocols (p > 0.05). A significant Protocol × Time interaction for VStiff resulted from the increase after the HL protocol being greater than that after the HV protocol (p = 0.03). The knee angles before the HL and HV protocols were significantly greater than those measured during the initial familiarization session (p = 0.001). Although neither squat protocol provided any benefit in improving JH, the heavy squat protocol produced greater increases in VStiff during the CMJ. Because of the increased VStiff caused by the HL protocol, volleyball coaches may consider using such protocols with their players to improve performance in jumps performed from a run such as the spike and on-court agility.

The Yo-Yo IR2 test: physiological response, reliability, and application to elite soccer.

Abstract Oberacker, LM, Davis, SE, Haff, GG, Witmer, CA, and Moir, GL. The Yo-Yo IR2 test: physiological response, reliability, and application to elite soccer. J Strength Cond Res 26(10): 2734–2740, 2012—The purpose of this study was to compare the effects of resistance training performed on either a stable or unstable surface on performance tests in female soccer players. Nineteen National Collegiate Athletic Association Division II female soccer players were assigned to either an unstable training group (UST: 19.0 ± 0.47 years; 1.69 ± 6.4 m; 67.8 ± 7.7 kg) or a stable training group (ST: 19.6 ± 0.49 years; 1.64 ± 3.2 m; 62.7 ± 6.27 kg). Player positions were distributed evenly between the groups. Both the groups followed a 5-week periodized resistance training program designed to develop maximum muscular strength. The groups performed the same exercises during each workout, with the UST performing 2 of the exercises in each session on an unstable surface. Pretraining and posttraining measures of straight-line sprint speed, planned and reactive agility, aerobic capacity, and countermovement vertical jump (CMJ) were taken. Significant main effects for time were reported for straight-line sprint speed, planned agility, and reactive agility with both groups demonstrating improvements during the posttraining testing session. The ST demonstrated a significant increase in CMJ during the posttraining session (change in mean: 0.04 m) in contrast to the decline demonstrated by the UST (change in mean: −0.01 m). Performing resistance training exercises on an unstable surface confers no advantage over traditional resistance training exercises for improving the speed, agility, and aerobic capacity of female soccer players. Furthermore, the use of an unstable surface may inhibit the effects of resistance training on vertical jump height, an important variable in soccer performance.

Effect of cluster set configurations on mechanical variables during the deadlift exercise.

The purpose of the present study was to investigate the effects of different configurations of repetitions within a set of deadlifts on the mechanical variables of concentric force, concentric time under tension, impulse, work, power, and fatigue. Eleven resistance trained men (age: 21.9 ± 1.0 years; deadlift 1 repetition maximum: 183.2 ± 38.3 kg) performed four repetitions of the deadlift exercise with a load equivalent to 90% of 1 repetition maximum under three different set configurations: Traditional (continuous repetitions); Doubles cluster (repetitions 1 and 2, and 3 and 4 performed continuously with a 30 s rest inserted between repetitions 2 and 3); Singles cluster (30 s rest provided between repetitions). The order of the sessions was counterbalanced across the subjects and the mechanical variables were calculated during each repetition from the synchronized signals recorded from force platforms and a motion analysis system. Relative to the Traditional set, the insertion of rest periods in the cluster set configurations resulted in greater time under tension (p < 0.001) and therefore, greater impulse (p < 0.001) during the repetitions. Reductions in power were observed during the cluster sets compared to the Traditional set (p = 0.001). The Doubles cluster set resulted in greater fatigue scores for power compared to the Traditional set (p = 0.04). The influence of cluster sets on mechanical variables appears to be mediated by the mechanical characteristics of the exercise (i.e. stretch-shortening cycle) and the competing physiological mechanisms of fatigue and potentiation.

Mechanical analysis of the acute effects of a heavy resistance exercise warm-up on agility performance in court-sport athletes.

Abstract The purpose of this study was to determine the acute effects of heavy resistance exercise on agility performance in court-sport athletes. Five men (age: 20.6 ± 1.9 years; body mass: 79.36 ± 11.74 kg; body height: 1.93 ± 0.09 m) and five women (age 21.2 ± 2.7 years; body mass: 65.8 ± 10.18 kg; body height 1.77 ± 0.08 m) volunteered to participate in the present study. All subjects were NCAA Division II athletes who currently participated in tennis or basketball and all had previous resistance training experience of at least one year. In a counterbalanced design, agility performance during a 10 m shuttle test was assessed following either a dynamic warm-up (DW) or heavy resistance warm-up (HRW) protocol. The HRW protocol consisted of three sets of squats at 50, 60, and 90% of 1-RM. Agility performance was captured using an eight camera motion analysis system and the mechanical variables of stride length, stride frequency, stance time, flight time, average ground reaction force, as well as agility time were recorded. No significant differences were reported for the HRW and DW protocols for any of the mechanical variables (p>0.05), although there was a trend towards the HRW protocol producing faster agility times compared to the control protocol (p = 0.074). Based on the trend towards a significant effect, as well as individual results it is possible that HRW protocols could be used as an acute method to improve agility performance in some court-sport athletes.

The development of a repetition-load scheme for the eccentric-only bench press exercise.

Abstract The purpose of the present study was to develop a repetition-load scheme for the eccentric-only bench press exercise. Nine resistance trained men (age: 21.6 ± 1.0 years; 1-repetition maximum [RM] bench press: 137.7 ± 30.4 kg) attended four testing sessions during a four week period. During the first session each subject’s 1-RM bench press load utilizing the stretch-shortening cycle was determined. During the remaining sessions they performed eccentric-only repetitions to failure using supra-maximal loads equivalent to 110%, 120% and 130% of their 1-RM value with a constant cadence (30 reps·min-1). Force plates and a three dimensional motion analysis system were used during these final three sessions in order to evaluate kinematic and kinetic variables. More repetitions were completed during the 110% 1-RM condition compared to the 130% 1-RM condition (p=0.01). Mean total work (p=0.046) as well as vertical force (p=0.049), vertical work (p=0.017), and vertical power output (p=0.05) were significantly greater during the 130% 1-RM condition compared to the 110% 1-RM condition. A linear function was fitted to the number of repetitions completed under each load condition that allowed the determination of the maximum number of repetitions that could be completed under other supra-maximal loads. This linear function predicted an eccentric-only 1-RM in the bench press with a load equivalent to 164.8% 1-RM, producing a load of 227.0 ± 50.0 kg. The repetition-load scheme presented here should provide a starting point for researchers to investigate the kinematic, kinetic and metabolic responses to eccentric-only bench press workouts.

The Effects Of Aerobic, Concurrent, And Resistance Exercise On Compensatory Eating Behaviors: 1925 Board #186 May 31 2

Obesity is a worldwide epidemic and can be defined as a disorder of positive energy balance, which occurs when the amount of energy consumed is greater than the amount of energy expended. PURPOSE: To observe the differences in compensatory eating behaviors between four groups (aerobic training, concurrent training, resistance training, and a non-exercise control) in recreationally active, resistance trained, collegeaged subjects. METHODS: Ten recreationally active college-aged (21.7 ± 1.3yrs) males and females participated in this study. A 5-week, randomized, crossover design with one full week between each session. Preliminary assessments consisted of a PAR-Q, informed consent, body composition, rep-set best, and VO2max. Aerobic exercise (AE) consisted of 30-minutes of cycling at 70% HRmax. Resistance exercise (RE) consisted of seven, full-body circuit of three sets of 12 repetitions at 70% set-rep best. Concurrent exercise (CE) consisted of four resistance exercises at the same intensity with 15-minutes of cycling at 70% HRmax. The control (CON) consisted of 30-minutes of sitting. Food logs via MyFitnessPal were required for the 24-hour period following each session. SPSS 24.0 was used for data analysis using one-way and two-way ANOVAS and deltas. Level of significance was set at p ≤ 0.05. RESULTS: There were no significant difference in total caloric (CON: 2,145 ± 807.9kcal, AE: 2,040 ± 657.2kcal, CE: 1,973 ± 764.8kcal, RE: 2,354 ± 1,077.0kcal, p = 0.743), carbohydrate (CON: 219 ± 66.4g, AE: 244 ± 87.3g, CE: 204 ± 55.4g, RE: 237 ± 94.9g, = 0.657), fat (CON: 57 ± 21.9g, AE: 58 ± 24.0g, CE: 59 ± 31.3g, RE: 63 ± 23.8g, p = 0.964), or protein intake (CON: 97 ± 48.6g, AE: 101 ± 48.0g, CE: 89 ± 53.4g, RE: 99 ± 46.4g, p = 0.942), HR (CON: 77 ± 10.3bpm, AE: 151 ± 21.9bpm, CE: 153 ± 16.2bpm, RE: 136 ± 15.8bpm, p = 0.122), or RPE (CON: 6 ± 0.0, AE: 11 ± 2.1, CE: 12 ± 1.9, RE: 10 ± 2.7, p = 0.147) between the four sessions. CONCLUSION: These findings demonstrate that the exercise-induced caloric deficit was not compensated via an increase in caloric and/or macronutrient intake, therefore, resulting in a negative energy balance. Further, the aforementioned findings provide evidence that exercise is a viable mechanism to create an energy deficit, which can ideally lead to successful weight loss.

The Effects Of An Acute Bout Of Resistance Training On College-aged Male 24hr Rmr: 1785 Board #46 May 31 2

Connor M. Saker, Chad A. Witmer, Shala E. Davis, Gavin L. Moir East Stroudsburg University of Pennsylvania, East Stroudsburg, PA It has been demonstrated that increasing caloric expenditure through exercise participation is one mechanism by which to modify caloric balance in favor of weight loss. While chronic resistance training (RT) has been demonstrated to elevate resting metabolic rate (RMR) due to increased lean mass, there has been less research on the acute effects of a single bout of resistance training on RMR. Thus the effects of acute RT on 24 h RMR may provide insight to another mechanism by which RT may positively affect energy expenditure. PURPOSE: To determine the effects of an acute bout of resistance training on the 24 h RMR of college-aged males. METHODS: Ten healthy men aged 18-24 yr performed 8 exercises: single leg dumbbell step-ups, bent over dumbbell row, single leg lunge, barbell bench press, back squat, barbell shoulder press, biceps curls and triceps extensions (2 sets, 10 repetitions, 2 min recovery, 70% 1RM & 8RM) following ACSM Guidelines for RT. Subjects reported for testing following a 12 h fast and engaged in 7, 30 min RMR measurements over the next 24 h (2 pre-exercise, 5 post exercise). Diet was controlled during the entire 24 h period. Subjects completed both an experimental (RT) and control (no exercise) day separated by 1 week. RESULTS: RMR (kcal) data was analyzed using a 1 way ANOVA with repeated measures on 2 factors (group and time). Statistical analysis revealed that there was no significant main effect for group (2179.58± 44.82 kcal vs. 2143.16 ± 44.82 kcal; F = .330, p = .567) or group x time interaction (F =.592, p =.736, Table 1). There was a significant main effect for time (F = 5.126, p < .001). CONCLUSION: We conclude that an acute bout of RT, following ACSM guidelines, did not significantly impact RMR in RT males 24 h post-exercise.