Megan A. Wong

Acute Effects of Static vs. Ballistic Stretching on Strength and Muscular Fatigue Between Ballet Dancers and Resistance Trained Women.

Abstract Lima, CD, Brown, LE, Wong, MA, Leyva, WD, Pinto, RS, Cadore, EL, and Ruas, CV. Acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. J Strength Cond Res 30(11): 3220–3227, 2016—Stretching is used to increase joint range of motion, but the acute effects can decrease muscle strength. However, this may depend on the population or mode of stretching. The purpose of this study was to compare the acute effects of static vs. ballistic stretching on strength and muscular fatigue between ballet dancers and resistance-trained women. Fifteen resistance-trained women (age 23.8 ± 1.80 years, mass 67.47 ± 7.77 kg, height 168.30 ± 5.53 cm) and 12 ballet dancers (age 22.8 ± 3.04 years, mass 58.67 ± 5.65 kg, height 168.00 ± 7.69 cm) performed 5 days of testing. The first day was control (no stretching), whereas the other 4 days were static or ballistic stretching in a counterbalanced order. Range of motion, strength, and fatigue tests were also performed. Both groups demonstrated a significant decrease in hamstrings strength after static (102.71 ± 2.67 N·m) and ballistic stretching (99.49 ± 2.61 N·m) compared with control (113.059 ± 3.25 N·m), with no changes in quadriceps strength. For fatigue, only ballet dancers demonstrated a decrease from control (71.79 ± 4.88%) to ballistic (65.65 ± 8.19%), but no difference with static (65.01 ± 12.29%). These findings suggest that stretching decreases hamstrings strength similarly in ballet dancers and resistance-trained women, with no differences between modes of stretching. However, ballistic stretching only decreased muscular fatigue in ballet dancers, but not in resistance-trained women. Therefore, no stretching should be performed before strength performance. However, ballistic stretching may decrease acute muscular fatigue in ballet dancers.

Influence of Rest Intervals After Assisted Sprinting on Bodyweight Sprint Times in Female Collegiate Soccer Players

Abstract Nealer, AL, Dunnick, DD, Malyszek, KK, Wong, MA, Costa, PB, Coburn, JW, and Brown, LE. Influence of rest intervals after assisted sprinting on bodyweight sprint times in female collegiate soccer players. J Strength Cond Res 31(1): 88–94, 2017—Speed is a crucial element an athlete must possess to be successful. In soccer, the ability to accelerate faster than your opponent can result in being first to reach a ball on a breakaway or stopping a counter attack. A unique way to train explosive movements is to evoke postactivation potentiation (PAP) in the working muscles. Traditionally, an overload stimulus with a long rest period is used, but a model using an overspeed stimulus with shorter rest periods is less understood. Therefore, the purpose of this study was to determine the acute effects of varied rest intervals after assisted sprinting on bodyweight sprint time. Twenty-four female soccer players were split into 2 groups: recreational (n:11; age:20 ± 1.67 year; ht:162.30 ± 4.35 cm; mass:61.02 ± 8.78 kg) and collegiate athletes (n:13; age:19.76 ± 0.83 year; ht:166.85 ± 5.98 cm; mass:61.23 ± 3.77 kg). All participants attended 5 separate sessions, performed a dynamic warm up, then executed one 20 m sprint (with 5 m splits) at 30% bodyweight assistance (BWA). They then rested for 30 seconds, 1, 2, or 4 minutes in random order, followed by one bodyweight sprint with no BWA. Baseline sprint times were measured without BWA on the initial session of testing. Results revealed no difference in sprint time for the full 20 m distance in either group. However, sprint time was significantly decreased for the 0–5 m split only for the athletes after 1 minute (1.15 ± 0.06 second) and 2 minute (1.16 ± 0.06 second) rest compared with baseline (1.21 ± 0.04 second). Therefore, trained athletes should rest 1 or 2 minutes after 30% BWA supramaximal sprinting for increased bodyweight sprint speed.

Acute Effects of Eccentric Overload on Concentric Front Squat Performance.

Abstract Munger, CN, Archer, DC, Leyva, WD, Wong, MA, Coburn, JW, Costa, PB, and Brown, LE. Acute effects of eccentric overload on concentric front squat performance. J Strength Cond Res 31(5): 1192–1197, 2017—Eccentric overload is used to enhance performance. The purpose of this study was to investigate the acute effects of eccentric overload on concentric front squat performance. Twenty resistance-trained men (age = 23.80 ± 1.82 years, height = 176.95 ± 5.21 cm, mass = 83.49 ± 10.43 kg, 1 repetition maximum [1RM] front squat = 131.02 ± 21.32 kg) volunteered. A dynamic warm-up and warm-up sets of front squat were performed. Eccentric hooks were added to the barbell. They descended for 3 seconds, until eccentric hooks released, and performed the concentric phase as fast as possible. There were 3 randomly ordered conditions with the concentric phase always at 90% 1RM and the eccentric phase at 105, 110, and 120% of 1RM. Two repetitions were performed for each condition. A repeated measures analysis of variance was used to determine differences. For peak velocity, there were main effects for time and condition (p < 0.05), where post (1.01 ± 0.10 m·s−1) was greater than pre (0.96 ± 0.11 m·s−1) and 120% (1.03 ± 1.11 m·s−1) was greater than 105% (0.99 ± 0.13 m·s−1). For peak power, there was a main effect for condition where 120% (2,225.00 ± 432.37 W) was greater than 105% (2,021.84 ± 563.53 W). For peak ground reaction force, there were main effects for time and condition, where post was greater than pre and 120% was greater than 105%. For the rate of force development, there was no interaction or main effects. Eccentric overload enhanced concentric velocity and power; therefore, it can be used by strength coaches and athletes during the power phase of a training program. It can also be used to prescribe supramaximal loads and could be a tool to supplement the clean exercise because the front squat is a precursor.

Bench press and pushup repetitions to failure with equated load

The bench press and pushup are commonly used for training upper body muscular strength and endurance. Although they are often used interchangeably, differences between the two relative to body mass load are unknown. Furthermore, sex differences may exist due to anthropometric body mass specificity. The purpose of this study was to evaluate the relationship between the pushup and bench press when performing repetitions to failure with an equated load. On day 1, 25 recreationally trained subjects (16 men, age = 23.00 ± 2.36 years, height = 178.19 ± 9.61 cm, mass = 74.80 ± 13.44 kg; 9 women, age = 23.11 ± 2.71 years, height = 160.78 ± 5.95 cm, mass = 53.63 ± 5.60 kg), performed a one repetition maximum bench press and an isometric pushup on a force plate to determine bodyweight load supported in both the up and down positions. Grip width on the bench press was measured as the distance between middle fingers and was used for hand placement during pushups. For the down position, a safety squat device was placed on the right triceps to signal that the upper arms were parallel to the ground, while for the up position, triceps were perpendicular to the floor. Days 2 and 3 consisted of performing repetitions to failure for either the bench press or pushup exercise with a load that was equal to the average relative bodyweight force of the up and down pushup positions. For the pushup, subjects followed a 60 beats per minute tempo and the test was terminated if they failed to complete a full repetition; they could not maintain cadence or there were three faults in form. For the bench press, they followed the same 60 s tempo and the test was terminated if they failed to complete a full repetition or could not maintain cadence. A 2 (exercise: bench press, pushup) × 2 (sex: men, women) mixed factor ANOVA demonstrated no interaction, but there were significant (P < 0.05) main effects for exercise and sex where more repetitions were performed in the pushup (19.36 ± 11.68 reps) than the bench press (11.40 ± 8.38 reps) exercise. Also, men performed significantly more repetitions to failure (men =20.22 ± 8.20 reps, women = 6.78 ± 5.69 reps). For combined sexes, there was a significant (P < 0.05), strong relationship (r = 0.82) between bench press and pushup repetitions to failure. For men, there was a significant (P < 0.05), strong relationship (r = 0.81), while for women, there was a moderate relationship (r = 0.76). Men had significantly (P < 0.05) greater bench press one repetition maximum (men = 99.29 ± 23.98 kg, women = 42.17 ± 8.88 kg), percentage of body mass supported as an average of the up and down positions (men = 74.33 ± 2.57%, women = 69.70 ± 2.63%) and bench press one repetition maximum relative to their body mass (men = 1.32 ± 0.22%, women = 0.79 ± 0.13%). The bench press and pushup are two distinct upper body exercises for repetitions to failure due to upper body musculature and body position sex differences. Choice of the pushup or bench press exercise should be based on training goal and sex.