Jakob L. Vingren

Effects of Stretching on Upper-body Muscular Performance

Torres, EM, Kraemer, WJ, Vingren, JL, Volek, JS, Hatfield, DL, Spiering, BA, Ho, JY, Fragala, MS, Thomas, GA, Anderson, JM, Häkkinen, K, and Maresh, CM. Effects of stretching on upper-body muscular performance. J Strength Cond Res 22: 1279-1285, 2008-The purpose of this investigation was to examine the influence of upper-body static stretching and dynamic stretching on upper-body muscular performance. Eleven healthy men, who were National Collegiate Athletic Association Division I track and field athletes (age, 19.6 ± 1.7 years; body mass, 93.7 ± 13.8 kg; height, 183.6 ± 4.6 cm; bench press 1 repetition maximum [1RM], 106.2 ± 23.0 kg), participated in this study. Over 4 sessions, subjects participated in 4 different stretching protocols (i.e., no stretching, static stretching, dynamic stretching, and combined static and dynamic stretching) in a balanced randomized order followed by 4 tests: 30% of 1 RM bench throw, isometric bench press, overhead medicine ball throw, and lateral medicine ball throw. Depending on the exercise, test peak power (Pmax), peak force (Fmax), peak acceleration (Amax), peak velocity (Vmax), and peak displacement (Dmax) were measured. There were no differences among stretch trials for Pmax, Fmax, Amax, Vmax, or Dmax for the bench throw or for Fmax for the isometric bench press. For the overhead medicine ball throw, there were no differences among stretch trials for Vmax or Dmax. For the lateral medicine ball throw, there was no difference in Vmax among stretch trials; however, Dmax was significantly larger (p ≤ 0.05) for the static and dynamic condition compared to the static-only condition. In general, there was no short-term effect of stretching on upper-body muscular performance in young adult male athletes, regardless of stretch mode, potentially due to the amount of rest used after stretching before the performances. Since throwing performance was largely unaffected by static or dynamic upper-body stretching, athletes competing in the field events could perform upper-body stretching, if enough time were allowed before the performance. However, prior studies on lower-body musculature have demonstrated dramatic negative effects on speed and power. Therefore, it is recommended that a dynamic warm-up be used for the entire warm-up.

Effects of amino acids supplement on physiological adaptations to resistance training

INTRODUCTION Previous research has demonstrated that ingestion of essential amino acids and their metabolites induce anabolic effects with the potential to augment gains in lean body mass and strength after resistance exercise training. PURPOSE The purpose of the present study was to examine the effects of an essential amino acid-based formula (Muscle Armor (MA); Abbott Laboratories, Abbott Park, IL) containing beta-hydroxy-beta-methylbutyrate (HMB) on hormonal and muscle damage markers in response to 12 wk of resistance exercise. METHODS Seventeen healthy men (mean body mass: 77.9 +/- 7.2 kg; mean height: 174.3 +/- 12.4 cm; mean age: 22.9 +/- 3.8 yr) were matched and randomized into two groups and performed 12 wk of periodized heavy resistance training while supplementing with either MA or an isocaloric, isonitrogenous placebo (CON). Every 2 wk during the 12-wk intervention, resting blood draws were obtained, and muscle strength and power were measured. In addition, blood draws were obtained before, during, and after a standardized resistance exercise challenge performed pre-, mid-, and posttraining. RESULTS Lean body mass, muscle strength, and muscle power significantly (P <or= 0.05) increased in both groups after training; however, MA supplementation augmented these responses to a significantly greater extent when compared with the CON group. MA supplementation promoted increases in resting and exercise-induced testosterone and resting growth hormone concentrations. In addition, MA reduced preexercise cortisol concentrations. Throughout the training protocol, MA attenuated circulating creatine kinase and malondealdehyde compared with the CON group, suggesting that MA might have influenced a reduction in muscle damage. CONCLUSION MA supplementation beneficially affected training-induced changes in lean body mass, muscle strength, and power, as well as hormonal responses and markers of muscle damage in response to 12 wk of resistance exercise training when compared with an isonitrogenous control.

Elevated endogenous testosterone concentrations potentiate muscle androgen receptor responses to resistance exercise.

The purpose of this study was to determine the influence of endogenous circulating testosterone (T) on muscle androgen receptor (AR) responses to acute resistance exercise (RE). Six healthy men (26+/-4 years; 176+/-5 cm; 75.8+/-11.4 kg) performed a knee extension exercise protocol on two occasions separated by 1-3 weeks. Rest preceded one trial (i.e., control [CON] trial) and a high-volume upper-body RE protocol designed to increase circulating T preceded the other trial (i.e., high T [HT] trial). Serial blood samples were obtained throughout each trial to determine circulating T concentrations. Biopsies of the vastus lateralis were obtained pre-RE (REST), 10-min post-RE (+10), and 180-min post-RE (+180) to determine muscle AR content. Circulating T concentrations remained stable during CON. Alternately, HT significantly (p< or =0.05) increased T concentrations above resting values (+16%). Testosterone area-under-the-time curve during HT exceeded CON by 14%. AR content remained stable from REST to +10 in both trials. Compared to the corresponding +10 value, muscle AR content at +180 tended to decrease during CON (-33%; p=0.10) but remained stable during HT (+40%; p=0.17). Muscle AR content at +180 during the HT trial exceeded the corresponding CON value. In conclusion, acute elevations in circulating T potentiated muscle AR content following RE.

Effects of Elevated Circulating Hormones on Resistance Exercise-induced Akt Signaling

PURPOSE Hormones and muscle contraction alter protein kinase B (Akt) signaling via distinct mechanisms. Therefore, the purpose of this study was to determine whether physiologically elevated circulating hormones modulate resistance exercise (RE)-induced signaling of Akt and its downstream targets. We hypothesized that elevated circulating hormones would potentiate the signaling response. METHODS Seven healthy men (mean +/- SD age, 27 +/- 4 yr; body mass, 79.1 +/- 13.6 kg; body fat, 16% +/- 7%) performed two identical lower-body RE protocols (five sets of five maximal repetitions of knee extensions) in a randomized order and separated by 1-3 wk: one protocol was preceded by rest [low-circulating hormonal concentration (LHC) trial], and the other was preceded by a bout of high-volume upper-body RE using short rest periods designed to elicit a large increase in circulating hormones [high-circulating hormonal concentration (HHC) trial]. RESULTS The HHC trial invoked significantly (P < or = 0.05) greater growth hormone (GH) and cortisol concentrations compared with the LHC trial. There were minimal differences between trials in insulin and insulin-like growth factor-I (IGF-I) concentrations. Contrary to our hypothesis, 70-kDa ribosomal protein S6 kinase (p70 S6K) threonine (Thr) 389 phosphorylation within the vastus lateralis was attenuated at 180 min post-RE during the HHC trial. RE did not affect Akt or glycogen synthase kinase-3beta (GSK-3beta) phosphorylation nor were there differences between trials. Immediately post-RE, eukaryotic initiation factor (eIF) 4E binding protein-1 (4E-BP1) phosphorylation declined, and adenosine monophosphate-activated protein kinase (AMPK) phosphorylation increased; however, there were no differences between trials in these variables. CONCLUSION p70 S6K Thr 389 phosphorylation was attenuated during the HHC trial despite dramatically greater (>2.5-fold) circulating GH concentrations; this was potentially due to cortisol-induced inhibition of p70 S6K Thr 389 phosphorylation.

Hormonal responses to a 160-km race across frozen Alaska

Background: Severe physical and environmental stress seems to have a suppressive effect on the hypothalamic–pituitary–gonadal (HPG) axis in men. Examining hormonal responses to an extreme 160-km competition across frozen Alaska provides a unique opportunity to study this intense stress. Objective: To examine hormonal responses to an ultra-endurance race. Methods: Blood samples were obtained from 16 men before and after racing and analyzed for testosterone, interleukin-6 (IL-6), growth hormone (GH) and cortisol. Six subjects (mean (SD) age 42 (7) years; body mass 78.9 (7.1) kg; height 1.78 (0.05) m raced by bicycle (cyclists) and 10 subjects (age 35 (9) years; body mass 77.9 (10.6) kg; height, 1.82 (0.05) m) raced by foot (runners). Mean (SD) finish times were 21.83 (6.27) and 33.98 (6.12) h, respectively. Results: In cyclists there were significant (p⩽0.05) mean (SD) pre-race to post-race increases in cortisol (254.83 (135.26) to 535.99 (232.22) nmol/l), GH (0.12 (0.23) to 3.21 (3.33) µg/ml) and IL-6 (2.36 (0.42) to 10.15 (3.28) pg/ml), and a significant decrease in testosterone (13.81 (3.19) to 5.59 (3.74) nmol/l). Similarly, in runners there were significant pre-race to post-race increases in cortisol (142.09 (50.74) to 452.21 (163.40) ng/ml), GH (0.12 (0.23) to 3.21 (3.33) µg/ml) and IL-6 (2.42 (0.68) to 12.25 (1.78) pg/ml), and a significant decrease in testosterone (12.32 (4.47) to 6.96 (3.19) nmol/l). There were no significant differences in the hormonal levels between cyclists and runners (p>0.05). Conclusions: These data suggest a suppression of the hypopituitary–gonadal axis potentially mediated by amplification of adrenal stress responses to such an ultra-endurance race in environmentally stressful conditions.

Effect of resistance exercise on muscle steroidogenesis

Circulating testosterone is elevated acutely following resistance exercise (RE) and is an important anabolic hormone for muscle adaptations to resistance training. The purpose of this study was to examine the acute effect of heavy RE on intracrine muscle testosterone production in young resistance-trained men and women. Fifteen young, highly resistance-trained men (n = 8; 21 +/- 1 yr, 175.3 +/- 6.7 cm, 90.8 +/- 11.6 kg) and women (n = 7; 24 +/- 5 yr, 164.6 +/- 6.7 cm, 76.4 +/- 15.6 kg) completed 6 sets of 10 repetitions of Smith machine squats with 80% of their 1-repetition maximum. Before RE and 10 and 70 min after RE, muscle biopsies were obtained from the vastus lateralis. Before RE, after 3 and 6 sets of squats, and 5, 15, 30, and 70 min into recovery from RE, blood samples were obtained using venipuncture from an antecubital vein. Muscle samples were analyzed for testosterone, 17beta-hydroxysteroid dehydrogenase (HSD) type 3, and 3beta-HSD type 1 and 2 content. Blood samples were analyzed for glucose and lactate concentrations. No changes were found for muscle testosterone, 3beta-HSD type 1 and 2, and 17beta-HSD type 3 concentrations. However, a change in protein migration in the Bis-Tris gel was observed for 17beta-HSD type 3 postexercise; this change in migration indicated an approximately 2.8 kDa increase in molecular mass. These findings indicate that species differences in muscle testosterone production may exist between rats and humans. In humans, muscle testosterone concentrations do not appear to be affected by RE. This study expands on the current knowledge obtained from animal studies by examining resting and postexercise concentrations of muscle testosterone and steroidogenic enzymes in humans.

Effects of Carnitine Supplementation on Flow-Mediated Dilation and Vascular Inflammatory Responses to a High-Fat Meal in Healthy Young Adults

Because carnitine has been shown to decrease oxidative stress and improve endothelial cell functioning, we examined the effects of carnitine supplementation on postprandial flow-mediated dilation (FMD) and circulating biomarkers of inflammation and oxidative stress after a high-fat meal. A randomized, double-blind, placebo-controlled, crossover study design was used. Thirty men and women (age 30 +/- 8 year, body mass 72.9 +/- 17.1 kg, body fat 13.0 +/- 6.4%) participated in 2 vascular testing days, each preceded by 3 weeks of supplementation with either 2 g/day of L-Carnitine (L-Carnitine L-Tartrate) or placebo with a 3- to 5-week washout period between trials. Brachial artery FMD in response to 5 minutes of upper arm occlusion and circulating markers of oxidative stress and inflammation were measured in the fasting state and after a standardized high-fat meal. After 3 weeks of supplementation, peak FMD in the fasting state was similar between the carnitine and placebo trials, averaging 6.6%. Peak FMD during the postprandial period decreased to 5.8% at 1.5 hours during placebo and increased to 7.7% during the carnitine trial (n = 30: p = 0.043 for supplement by time interaction effect). This improvement in postprandial vascular function was most dramatic in subjects who showed a decrease in peak FMD in response to the meal (n = 15: p = 0.003 for supplement by time interaction effect). There was a significant increase in postprandial lipemia and plasma interleukin-6 but no effect of supplementation. There were no significant postprandial changes or supplement effects for plasma tumor necrosis factor-alpha and malondialdehyde. In conclusion, consistent with other work showing a beneficial effect of carnitine on vascular function, these findings indicate that carnitine supplementation in healthy individuals improves postprandial FMD after a high-fat meal.

Effects of L-carnitine L-tartrate supplementation on muscle oxygenation responses to resistance exercise.

Spiering, BA, Kraemer, WJ, Hatfield, DL, Vingren, JL, Fragala, MS, Ho, J-Y, Thomas, GA, Häkkinen, K, and Volek, JS. Effects of L-carnitine L-tartrate supplementation on muscle oxygenation responses to resistance exercise. J Strength Cond Res 22: 1130-1135, 2008-Previous research has shown that L-carnitine L-tartrate (LCLT) supplementation beneficially affects markers of hypoxic stress following resistance exercise. However, the mechanism of this response is unclear. Therefore, the primary purpose of this study was to determine the effects of LCLT supplementation on muscle tissue oxygenation during and after multiple sets of squat exercise. Nine healthy, previously resistance-trained men (25.2 ± 6.years, 91.2 ± 10.2 kg, 180.2 ± 6.3 cm) ingested 2 g·d−1 of LCLT or an identical placebo for 23 days in a randomized, balanced, crossover, double-blind, placebo-controlled, repeated-measures study design. On day 21, forearm muscle oxygenation was measured during and after an upper arm occlusion protocol using near infrared spectroscopy (NIRS), which measures the balance of oxygen delivery in relation to oxygen consumption. On day 22, subjects performed 5 sets of 15 to 20 repetitions of squat exercise with corresponding measures of thigh muscle oxygenation, via NIRS, and serial blood draws. Compared to the placebo trial, muscle oxygenation was reduced in the LCLT trial during upper arm occlusion and following each set of resistance exercise. Despite reduced oxygenation, plasma malondealdehyde, a marker of membrane damage, was attenuated during the LCLT trial. There were no differences between trials in the vasoactive substance prostacyclin. In conclusion, because oxygen delivery was occluded during the forearm protocol, it is proposed that enhanced oxygen consumption mediated the reduced muscle oxygenation during the LCLT trial. Enhanced oxygen consumption would explain why hypoxic stress was attenuated with LCLT supplementation.

Factors Affecting Flutter Kicking Speed in Women Who Are Competitive and Recreational Swimmers

McCullough, AS, Kraemer, WJ, Volek, JS, Solomon-Hill, GF Jr, Hatfield, DL, Vingren, JL, Ho, JY, Fragala, MS, Thomas, GA, Häkkinen, K, and Maresh, CM. Factors affecting flutter kicking speed in women who are competitive and recreational swimmers. J Strength Cond Res 23(7): 2130-2136, 2009-The purpose of this study was to determine the relationships between possible predictive measures of a 50 m front crawl swimming and a 22.86 m flutter kicking speed. Ten women who were National Collegiate Athletic Association Division I collegiate swimmers and 10 women who were recreational swimmers (mean ± SD = 20.6 ± 1.6 years; 66.7 ± 10.3 kg; 166.7 ± 8.8 cm) volunteered for the study. Anthropometric measures were obtained including height, leg length, lower leg length, and foot length. Ankle flexibility was assessed by measuring ankle plantar flexion and ankle inversion. Lower body power was measured using a vertical jump. Swimming and kicking speed were measured as the time to complete a 50 m front crawl and a 22.86 m flutter kick, respectively. Significant moderate correlations were demonstrated between ankle plantar flexion and flutter kicking speed (r = 0.509); age and 22.86 m kick time (r = 0.608); age and 50 m swim time (r = 0.476); and 50 m swim time and 22.86 m kick time (r = 0.790). No significant correlations were observed between any of the anthropometric measurements or vertical jump power with either kicking or swimming speed. As anecdotally noted by swim coaches over the years, this study provides some actual data showing that ankle flexibility significantly influences flutter kick capability. Surprisingly, vertical jump power and body size were not strong predictors of kicking or swimming speed in this group of subjects. Strength and conditioning coaches, swim coaches, and athletes should evaluate and carefully develop ankle flexibility to positively contribute to kicking capabilities.

Relationship between off-ice testing variables and on-ice speed in women's collegiate synchronized figure skaters: implications for training.

Bower, ME, Kraemer, WJ, Potteiger, JA, Volek, JS, Hatfield, DA, Vingren, JL, Spiering, BA, Fragala, MS, Ho, JY, Thomas, GA, Earp, JE, Häkkinen, K, and Maresh, CM. Relationship between off-ice testing variables and on-ice speed in womens collegiate synchronized figure skaters: implications for traning. J Strength Cond Res 24(3): 831-839, 2010-The purpose of the current investigation was to identify any existing relationships between off-ice performance measures and on-ice performance quantified by speed and acceleration. Twenty-seven women (age 19 ± 1 year; body mass (59.5 ± 6.8 kg; height 164.6 ± 6.35 cm; body fat 23.2 ± 3.9%) who were collegiate synchronized figure skaters volunteered for the investigation. To examine the relationship between off-ice performance and on-ice speed and acceleration, collegiate synchronized skaters were evaluated on various performance tests over a 1-week period. Off-ice tests completed were peak torque for hip abduction and adduction, 40-yard sprint, vertical jump height, 30-second slide board stride count, and a 1-RM (repetition maximum) squat. On-ice tests included a timed single lap sprint, 4.5-minute (duration of long program) lap count, and an approximately 16.5-m (18-yard blue line to blue line) timed acceleration. Significance was set at P ≤ 0.05. This study showed 3 primary findings: (a) slide board stride count was the single best predictor for both single lap on-ice speed and acceleration accounting for 53.5% (adjusted R2 value) of the variance in the single lap test and 42.5% (adjusted R2 value) of the variance in acceleration times; (b) vertical jump height test was the second best predictor for both the single lap test and on-ice acceleration accounting for 36.6% and 39.9% (adjusted R2 values) of the variance in times recorded, respectively; and (c) the best combined predictors for the single lap speed test were slide board stride count and 40-yard dash (R2 = 0.675), whereas the best combined predictors for on-ice acceleration were slide board stride count and vertical jump height test (R2 = 0.571). Conditioning for synchronized skaters to enhance performance of on-the-ice speed and acceleration should include slide board training implementation of plyometric and linear speed training while developing and maintaining 1-RM strength to support power capabilities.