Effect of Using a Counter-balanced Smith Machine on Performance Measurements for Concentric-Only Bench Press Throws

Bench press throws using a Smith machine are often used for assessment and training of upper body power. Concentric only bench press throws (CON-BT) provide important information on an individual’s ability to produce force from a static start. Smith machines often utilize a counter-balance weight system to reduce the net load on the barbell; however, it is not known how counter-balance weight affects measurements of performance during a CON-BT. PURPOSE: To examine the effect of a counter-balance weight on CON-BT performance measurements. METHODS: 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg) performed 2 sets of 2 repetitions of CON-BT at 30% of their 1RM using a no counter-balanced (NCB) and a counter-balanced (CB) Smith machine. Total duration, peak power, peak force, and peak velocity were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used for further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Measurements for peak barbell power (NCB: 1169 ± 260 W, CB: 938 ± 262 W) and force (NCB: 695 ± 129 N, CB: 577 ± 134 N) were significantly greater (p\u3c0.05) for NCB compared to CB. The total duration of CON-BT was shorter for NCB (0.62 ± 0.41 s) compared to CB (0.78 ± 0.50 s). The peak GRF showed a trend (p\u3c0.10) for being lower for NCB (884 ± 213 N] compared to CB [912 ± 190 N). Peak EMG and peak velocity were unaffected by the use of counter-balance weight. CONCLUSION: The use of a CB Smith machine reduced barbell performance measurements (peak power and peak force) but increased the peak GRF during a CON-BT. A counter-balance weight becomes ineffective and the net external load increases during the CON-BT when the barbell accelerates faster than the gravitational constant pulls on the counter weight, thus explaining the lower performance measurements found for CB

Use of Counter-balanced Smith Machine Affects Performance Measurements for Rebound Bench Press Throws

Rebound bench presses throws (RBT), often performed on a Smith machine, are used for assessment and training of upper body power. During a RBT, the stretch-shortening cycle potentiates performance in the concentric movement. Smith machines frequently utilize a counter-balance weight to reduce the net load on the barbell; however, the use of counter-balance weight affects measures of performance for RBT. PURPOSE: To evaluate how the use of a counter-balanced Smith machine affects performance measures for RBT. METHODS: Performance measures for the no counter-balanced (NCB) and counter-balanced (CB) RBT were assessed for 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1-repetition maximum [1RM]: 107 ± 18 kg). Each participant performed 2 sets of 2 repetitions of RBT for each condition at 30 % of their 1RM. Peak power, peak force, peak concentric and eccentric velocities, and duration of eccentric and concentric phases were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used in further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Peak barbell measurements for power (NCB: 1220 ± 269 W, CB: 1069 ± 255 W), force (NCB: 906 ± 252 N, CB: 713 ± 143 N), and concentric (NCB: 2.54 ± 0.27 m•s-1, CB: 2.24 ± 0.32 m•s-1) and eccentric (NCB: -1.19 ± 0.46 m•s-1, CB: -0.95 ± 0.29 m•s-1) velocities were significantly (p\u3c0.05) higher for NCB compared to CB. The durations for the eccentric (NCB: 0.53 ± 0.16 s, CB: 0.64 ± 0.12 s) and concentric phases (NCB: 0.58 ± 0.58 s, CB: 0.77 ± 0.82 s), and peak pectoral EMG (NCB: 91 ± 21 % of 1RM, CB: 101 ± 24 % of 1RM) were lower for NCB compared to CB. Peak EMG for deltoid and triceps and peak GRF were unaffected by the use of counter-balance weights. CONCLUSION: The use of CB equipment resulted in reduced performance measurements (peak power, peak force, and peak eccentric and concentric velocities) for the RBT compared to NCB equipment. The lower peak eccentric stretch velocity likely resulted in a less effective stretch-shortening cycle for CB compared to NCB and thus helps explain the lower performance measurements found for CB

Effect Of Combined Aerobic And Resistance Training On HPA Axis Reactivity In HIV+ Women Undergoing Treatment For Substance Abuse

Substance abuse and infection with human immunodeficiency virus (HIV) are chronic stressors that affect hypothalamic-pituitary-adrenal (HPA) axis function. The purpose of this study was to investigate the effect of combined aerobic and resistance training on HPA axis reactivity in women with HIV undergoing treatment for substance abuse. Sixteen women (mean ± SD; 41 ± 9 years, 164 ± 6 cm, 78.1 ± 17.1 kg, 36 ± 10 % body fat) infected with HIV and enrolled in an intensive 60-day in-patient substance addiction/abuse treatment program were recruited shortly after admission to the treatment facility. Participants were assigned to one of two groups using randomization: (1) supervised combined aerobic and resistance exercise sessions 3 times per week (EX) for six weeks or (2) no exercise training (Control) for six weeks. Before (PRE) and after (POST) the 6-week period participants completed a 10-min public speaking task (Trier Social Stress Test). Saliva samples were obtained before (baseline), immediately after, and every 10 min for 50 min after the task. Saliva samples were analyzed for cortisol. HPA axis reactivity was determined as the difference between the highest values after the test minus the baseline value. HPA axis reactivity did not differ between groups at PRE (EX: 1.9 ± 2.0 nmol•L-1; Control: 1.1 ± 2.7 nmol•L-1) or POST (EX: 1.7 ± 2.1 nmol•L-1; Control: 0.0 ± 1.3 nmol•L-1). Similarly no differences were found between PRE and POST although the reactivity for the Control group appeared to be reduced at POST. HIV+ women in early recovery from substance abuse appear to display blunted HPA axis reactivity. A combined aerobic and resistance training intervention did not affect this reactivity; although, the exercise intervention might have prevented a further decline in reactivity

Exploring the role of BMP7 gene expression in an In Vitro model of aging human skeletal muscle.

Sarcopenia is an age-related condition associated with rapid loss of skeletal muscle (SKM) tissue that affects mobility and quality of life of geriatric individuals. Mechanistic Target of Rapamycin (mTOR) and Protein Kinase B (AKT) have significant roles in SKM hypertrophy with responses to DNA damage and repair within SKM. However, mTOR and AKT expression is significantly decreased with age. Upstream of AKT, Bone Morphogenetic Protein (BMP7) is a member of the TGF-β signaling family that has been reported as a positive regulator of muscle hypertrophy through the Bmp–Smad1/5/8 signaling axis. PURPOSE: To use an in vitro model of aging muscle cells to investigate the role of BMP7 expression on protein synthesis. METHODS: Human SKM myoblasts were cultured and grown beyond mature myotube formation (typically day 6) to emulate aged SKM tissue (extracted on day 18). Groups included control cells (D6) and aged SKM myotubes (D18). Total RNA was extracted at the respective time points (days 6 & 18) and gene expression for BMP7, mTOR, and AKT was determined by qPCR. RESULTS: BMP7 expression was 7.73 fold greater for D18 compared to D6 (p \u3c 0.05). No differences were reported for AKT or mTOR. Data are expressed as fold changes. CONCLUSION: BMP7 expression, thought to be a positive regulator of muscle hypertrophy, was increased in the aging muscle cells of our model, despite our hypothesis that it would be decreased. However, BMP7’s downstream targets related to increased protein synthesis, mTOR and AKT, did not similarly increase from D6 to D18, which is constant with the phenomena of sarcopenia. This leads us to speculate that there may be additional mechanisms related to BMP7 activation and, despite increased signaling, may block protein synthesis at the level of AKT

Binge Drinking Following Resistance Exercise: Effect on Muscle Power Recovery

Alcohol impairs recovery of isokinetic performance following muscle damaging resistance exercise but no knowledge exists regarding alcohol’s effect on recovery of performance in explosive isotonic movements following resistance exercise that induces only limited muscle damage. Purpose: To investigate the effect of alcohol on recovery from resistance exercise for explosive performance measures. Methods: Nine healthy men (Mean ± SD: 24.8 ± 3.2 years, 176 ± 7 cm, 86.4 ± 14.6 kg) completed 2 identical acute heavy resistance exercise tests (AHRET) separated by 1 week. The AHRET consisted of 6 sets of 10 repetitions of smith machine squats at 80% of 1-repetition maximum (1-RM) with 2 min of rest between sets. From 10-20 minutes post-AHRET participants consumed either 190 proof grain alcohol (EtOH) equal to 1.086 g of alcohol per kg lean mass (82-122 ml total) or no alcohol (Placebo) diluted in an artificially sweetened and calorie free beverage. The participants were blinded to conditions and the order of conditions was counter-balanced. Blood alcohol concentration (BAC) was measured using a breathalyzer. Sixty-five minutes pre-exercise, participants ingested a meal replacement beverage (33.5 kJ per kg body mass). Before the AHRET (PRE) and the following morning (AM), participants performed three high pulls and three bench press throws with 30% of 1-RM, and 10 consecutive vertical jumps, all at maximal effort. Peak power was measured for all exercises. Muscle soreness was measured using analog scales at PRE and AM. Results: BAC peaked 60-90 min post-exercise in all participants (0.084 ± 0.017 g·dl-1) on alcohol ingestion days. No effect of alcohol was found for peak power in the high pull (EtOH, PRE: 1658 ± 432 W, AM: 1659 ± 260 W; Placebo, PRE: 1599 ± 397 W, AM: 1579 ± 301 W), bench press throw (EtOH, PRE: 1120 ± 276 W, AM: 1105 ± 295 W; Placebo, PRE: 1119 ± 202 W, AM: 1089 ± 257 W), or vertical jump (EtOH, PRE: 52.6 ± 13.5 W·kg-1, AM: 48.5 ± 6.3 W·kg-1; Placebo, PRE: 52.2 ± 9.4 W·kg-1, AM: 47.9 ± 9.0 W·kg-1). Leg soreness increased moderately from PRE to AM with no difference between conditions. CONCLUSION: A moderate BAC does not appear to affect explosive upper or lower body power capability on the morning following a heavy squat session that induces only limited muscle damage

The Effects of Cannabidiol Supplementation on Measures of Performance and Fatigue Following Eccentric Exercise

Following intense exercise, there is a period of time where performance is decreased. This period of reduced performance is characterized by several factors including myofibrillar disruption, reduced range-of-motion, inflammation, and an influx of enzymes and proteins. Cannabidiol (CBD) has been marketed as a recovery supplement capable of reducing markers of fatigue and inflammation following exercise, yet this claim has not been investigated. PURPOSE: The purpose of this study was to determine if CBD supplementation limits fatigue and expedites a return to performance following intense eccentric exercise. METHODS: A double-blind, crossover design with repeated measures was used. Twenty-four NCAA female athletes (age = 21.2 ± 1.8 yrs., height = 166.4 ± 8 cm, weight = 64.9 ± 9.1 kg) were randomized to either receive 5 mg/kg of CBD in pill form (Cannabidiol Life, Longwood, FL) or a matched weight placebo. Treatments were consumed two hours prior to, immediately following, and ten hours following muscle damage sessions. All participants consumed both treatments, with each separated by approximately 28 days to control for the menstrual cycle. To induce muscle damage, participants completed 10 sets of 10 repetitions of unilateral eccentric leg extension at 60°/sec on an isokinetic dynamometer (Biodex Medical Systems Inc., Shirley, NY). Concentrations of a blood marker indicative of muscle damage (myoglobin), in addition to measures of fatigue (visual analogue fatigue scale [VAFS]) and performance (vertical jump, peak dynamic knee extensor torque at 60, 180, and 300°/sec, and peak isometric knee extensor torque), were collected before and 4, 24, and 48 hours following muscle damaging sessions. A repeated measures MANOVA was conducted to analyze the performance measures, and separate repeated measures ANOVAs were conducted to analyze myoglobin concentrations and results from the VAFS with a significance level of 0.05. RESULTS: A significant increase (p = 0.002) in myoglobin levels was observed for both treatments 4 hours following the muscle damaging session but no significant differences (p \u3e 0.05) were observed between the CBD and placebo groups at any of the 4 measured time points. Peak torque at 60°/sec (p = 0.001) and peak isometric torque (p = 0.02) were significantly lower 24 hours following muscle damage, but none of the 5 measured performance variables were significantly different (p \u3e 0.05 for all) between the CBD and placebo treatment at any time point. Subjective fatigue as measured by the VAFS was not significantly different (p \u3e 0.05) between the CBD and placebo treatments at any measured time point. CONCLUSION: Cannabidiol supplementation was unable to reduce fatigue and restore performance when compared to a placebo in well-trained female participants. It does not appear that CBD supplementation is of beneficial use as a recovery supplement following intense exercise in athletes

Functional Movement Screentm Scores in Collegiate Track and Field Athletes in Relation to Injury Risk and Performance

Purpose: The purpose of this study was to examine the relationship between Functional Movement Screentm (FMS) scores, injury rate, and performance in collegiate track and field athletes. Methods: Forty seven male (n=17) and female (n=30) competitive track and field athletes at an NCAA Division I university volunteered for this study. As part of their regular team assessment, the athletes were evaluated on three separate occasions using the FMS tool: in August, one week prior to the start of university organized practice for the fall (T1); in December, one week prior to the end of the fall academic semester (T2); and in March, the week following the conclusion of the indoor competition season (T3). The FMS consists of the performance of seven fundamental movement patterns that are evaluated and scored by a trained professional. For each time point, athletes were divided into two categories based on total FMS score (≤14 and ≥15). Throughout the competitive season, injuries were tracked and categorized as either mild (no loss of practice or competition time) or moderate/severe (loss of practice or competition time). As part of an ongoing injury prevention program, athletes performed generalized corrective exercises for 15 min 2-3 times per week. The performance in the last event of the season (conference meet) was also recorded. Results: Average FMS scores significantly (p\u3c0.05) decreased across the three time points (Mean ± SD, T1: 15.5 ± 2.2, T2: 14.9 ± 1.8, T3: 14.7 ± 1.6) despite that generalized corrective exercises were performed. Analyses of results found no association between FMS scores and likelihood to sustain a moderate/severe injury. Athletes with a score of ≤14 on the FMS at T1 were 3.1 times more likely not to place in the top 8 at the conference meet. 53% of the athletes who had a score of ≥15 at T1 placed in the top 8 at the meet while only 27% of athletes with a score of ≤14 at T1 placed in the top 8 at the meet. Conclusion: FMS scores ≤14 indicate reduced performance ability but not increased likelihood of injury in track and field athletes

Influence of Race on the Female Athlete Triad

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Formoterol Stimulation In Vitro Influences Myogenic Regulatory Factors During Myogenesis in Human Skeletal Muscle Cells

The process of myogenesis within skeletal muscle (SKM) is essential for growth and repair and is coordinated via the expression of myogenic regulatory genes. Previous animal studies have reported that formoterol, a beta-adrenergic receptor agonist, has stimulating effects on genes related to SKM mitochondrial function and biogenesis, similar to effects found for exercise. Lesser known is the potential “exercise mimetic” influence that formoterol stimulation may have during the stages of myogenesis, especially in human SKM cells. PURPOSE: To investigate the effects of formoterol stimulation on expression of myogenic regulatory genes during myogenesis in human SKM cells. METHODS: Human SKM myoblasts (n = 6 per group) were cultured and differentiated until mature myotube formation (Day 6). Groups included control cells (CON) and cells stimulated by 30nM formoterol for 3h prior to RNA extraction points (FORM). Total RNA was extracted during mid-myogenesis (Day 4) and at terminal differentiation (Day 6) (a cell culture model of investigating myogenesis). Gene expression for Myogenic factor 5 (Myf5), Myogenic differentiation 1(MyoD), and Myogenin (MyoG) was determined by qPCR. Data was analyzed using repeated measures ANOVA. RESULTS: Myf5: There was no change for either condition for D4. D6 CON was lower than D4 CON (-0.25). D6 FORM was greater than D4 FORM (0.65) and D6 CON (0.75). MyoD: D4 FORM was lower than D4 CON (-0.57). D6 FORM was greater than D4 FORM (0.85) and lower than D6 CON (-0.16). D6 CON was lower than D4 CON (-0.33). MyoG: D4 FORM was lower than D4 CON (-0.72). D6 CON was lower than D4 CON (-0.44). D6 FORM was lower than D6 CON (-0.24). All reported differences are significant (p \u3c 0.05). Data are expressed as fold changes. CONCLUSION: As expected, for the CON group, Myf5, MyoD, and MyoG expression all decreased from D4 mid-myogenesis to D6 terminal myogenesis, indicating finalization of the myogenic gene program. For the FORM group, Myf5 expression was elevated at D6 compared to CON while MyoG and MyoD expression was lower than CON for D4 and D6. The interpretation is that FORM stimulation increased stimulus of D4 myoblast proliferation and, thus, delayed initiation of differentiation. These results, coupled with other preliminary data from our lab showing increased mitochondrial biogenesis with this model of investigation, suggests that this exercise mimetic stimulation may cause shift in the cell towards bioenergetic preference rather than fusion of myotubes