David R. Hooper

The effects of a customized over-the-counter mouth guard on neuromuscular force and power production in trained men and women.

Abstract Dunn-Lewis, C, Luk, H-Y, Comstock, BA, Szivak, TK, Hooper, DR, Kupchak, BR, Watts, AM, Putney, BJ, Hydren, JR, Volek, JS, Denegar, CR, and Kraemer, WJ. The effects of a customized over-the-counter mouth guard on neuromuscular force and power production in trained men and women. J Strength Cond Res 26(4): 1085–1093, 2012—Although mouth guards were originally designed for injury prevention, even elite athletes are now using performance mouth guards to improve athletic success. Both expensive custom models and over-the-counter models are available, but the efficacy is not well known. Some athletes remain wary of the perceived potential for detriments using a mouth guard to their performance. Thus, the purpose of this study was to examine various physical performance tests when using a mouth guard including a customized over-the-counter mouth guard. Twenty-six trained men (25 ± 4 years; 1.78 ± 0.07 m; 83.3 ± 11.4 kg) and 24 trained women (23 ± 3 years; 1.65 ± 0.08 m; 62.6 ± 7.8 kg) volunteered for the investigation. The subjects completed a familiarization period and then balanced and randomized treatment conditions that included: (a) a customized Power Balance performance mouth guard (PB MG); (b) a regular over the counter boil-and-bite mouth guard (Reg MG); and (c) a no mouth guard (No MG) treatment condition. At each visit, the subjects completed a testing protocol that was sequenced in the following order: sit-and-reach flexibility, medial-lateral balance, visual reaction time, vertical jump, 10-m sprint, bench throw, and plyo press power quotient (3PQ). Heart rate and rating of perceived exertion (RPE) were recorded around the 3PQ. Significance was set at p ⩽ 0.05. Expected significant sex differences existed for all power, strength, and speed variables. Bench throw power (watts) and force (newtons) were significantly higher under PB MG than either Reg MG or No MG or in both men and women. The 3PQ power and force production were higher than that for the other 2 treatments for the PB MG for men only. There were no significant differences for treatment conditions in the heart rate or RPE after the 3PQ test. Men were better able to maintain significantly higher 3PQ power production under PB MG treatment condition compared with the other 2 treatment conditions. Rate of power development was significantly higher in men for the vertical jump when using the PB MG compared with that for other treatment conditions in men only. No differences were observed in flexibility, balance, visual reaction time, or sprint time. The PB MG performance mouth guard improves performance of upper-body loaded power exercises in both men and women and lower body power exercise in men without compromising performance on any other performance parameters.

Effects of Fatigue From Resistance Training on Barbell Back Squat Biomechanics

Abstract Hooper, DR, Szivak, TK, Comstock, BA, Dunn-Lewis, C, Apicella, JM, Kelly, NA, Creighton, BC, Flanagan, SD, Looney, DP, Volek, JS, Maresh, CM, and Kraemer, WJ. Effects of fatigue from resistance training on barbell back squat biomechanics. J Strength Cond Res 28(4): 1127–1134, 2014—Exhaustive resistance training programs that have been previously referred to as extreme conditioning protocols have increased in popularity in military and civilian populations in recent years. However, because of their highly fatiguing nature, proprioception is likely altered during such programs that would significantly affect the safety and efficacy of such programs. Therefore, the purpose of this study was to assess the alterations in movement patterns that result from extreme conditioning protocols and to evaluate if these protocols can be deemed safe and effective. Twelve men (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg, body fat percentage 9.0 ± 2.2%) and 13 women (age 24.5 ± 3.8 years, height 166.9 ± 8.5 cm, weight 66.1 ± 9.2 kg, body fat percentage 18.6 ± 4.0%) with at least 6 months of resistance training experience involving barbell bench press, barbell deadlift, and barbell back squat performed a highly fatiguing resistance training workout. During the barbell back squat, a 2-dimensional analysis was performed where the knee and hip angles were recorded throughout the 55 repetitions of the workout. At the early stages of the protocol, knee angle was significantly lower in men and in women demonstrating less knee flexion. Also, hip angle was significantly lower early in the program in men and in women, demonstrating a greater forward lean. The technique changes that occur in high repetition sets do not favor optimal strength development and may increase the risk of injury, clearly questioning the safety and efficacy of such resistance training programming. This is likely a display of self-preservation by individuals who are faced with high repetition programs.

The effects of soy and whey protein supplementation on acute hormonal reponses to resistance exercise in men.

Objective: For many resistance-trained men concerns exist regarding the production of estrogen with the consumption of soy protein when training for muscle strength and size. Thus, the purpose of this investigation was to examine the effects of soy and whey protein supplementation on sex hormones following an acute bout of heavy resistance exercise in resistance trained men. Methods: Ten resistance-trained men (age 21.7 ± 2.8 [SD] years; height 175.0 ± 5.4 cm; weight 84.2 ± 9.1 kg) volunteered to participate in an investigation. Utilizing a within subject randomized crossover balanced placebo design, all subjects completed 3 experimental treatment conditions supplementing with whey protein isolate (WPI), soy protein isolate (SPI), and maltodextrin placebo control for 14 days with participants ingesting 20 g of their assigned supplement each morning at approximately the same time each day. Following supplementation, subjects performed an acute heavy resistance exercise test consisting of 6 sets of 10 repetitions in the squat exercise at 80% of the subjects one repetition maximum. Results: This investigation observed lower testosterone responses following supplementation with soy protein in addition to a positive blunted cortisol response with the use of whey protein at some recovery time points. Although sex hormone binding globulin (SHBG) was proposed as a possible mechanism for understanding changes in androgen content, SHBG did not differ between experimental treatments. Importantly, there were no significant differences between groups in changes in estradiol concentrations. Conclusion: Our main findings demonstrate that 14 days of supplementation with soy protein does appear to partially blunt serum testosterone. In addition, whey influences the response of cortisol following an acute bout of resistance exercise by blunting its increase during recovery. Protein supplementation alters the physiological responses to a commonly used exercise modality with some differences due to the type of protein utilized.

THE EFFECTS OF HIGH INTENSITY SHORT REST RESISTANCE EXERCISE ON MUSCLE DAMAGE MARKERS IN MEN AND WOMEN

Abstract Heavens, KR, Szivak, TK, Hooper, DR, Dunn-Lewis, C, Comstock, BA, Flanagan, SD, Looney, DP, Kupchak, BR, Maresh, CM, Volek, JS, and Kraemer, WJ. The effects of high intensity short rest resistance exercise on muscle damage markers in men and women. J Strength Cond Res 28(4): 1041–1049, 2014—Within and between sexes, universal load prescription (as assigned in extreme conditioning programs) creates extreme ranges in individual training intensities. Exercise intensity has been proposed to be the main factor determining the degree of muscle damage. Thus, the purpose of this study was to examine markers of muscle damage in resistance-trained men (n = 9) and women (n = 9) from a high intensity (HI) short rest (SR) (HI/SR) resistance exercise protocol. The HI/SR consisted of a descending pyramid scheme starting at 10 repetitions, decreasing 1 repetition per set for the back squat, bench press, and deadlift, as fast as possible. Blood was drawn pre-exercise (pre), immediately postexercise (IP), 15 minutes postexercise (+15), 60 minutes postexercise (+60), and 24 hours postexercise (+24). Women demonstrated significant increases in interleukin 6 (IL-6; IP), creatine kinase (CK; +24), myoglobin (IP, +15, +60), and a greater relative increase when compared with men (+15, +60). Men demonstrated significant increases in myoglobin (IP, +15, +60, +24), IL-6 (IP, +15), CK (IP, +60, +24), and testosterone (IP, +15). There were significant sex interactions observed in CK (IP, +60, +24) and testosterone (IP, +15, +60, +24). Women completed the protocol faster (women: 34:04 ± 9:40 minutes, men: 39:22 ± 14:43 minutes), and at a slightly higher intensity (women: 70.1 ± 3.5%, men 68.8 ± 3.1%); however, men performed significantly more work (men: 14384.6 ± 1854.5 kg, women: 8774.7 ± 1612.7 kg). Overall, women demonstrated a faster inflammatory response with increased acute damage, whereas men demonstrated a greater prolonged damage response. Therefore, strength and conditioning professionals need to be aware of the level of stress imposed on individuals when creating such volitional high intensity metabolic type workouts and allow for adequate progression and recovery from such workouts.

Adrenal Cortical Responses to High-intensity, Short Rest, Resistance Exercise in Men and Women

Abstract Szivak, TK, Hooper, DR, Dunn-Lewis, C, Comstock, BA, Kupchak, BR, Apicella, JM, Saenz, C, Maresh, CM, Denegar, CR, and Kraemer, WJ. Adrenal cortical responses to high-intensity, short rest, resistance exercise in men and women. J Strength Cond Res 27(3): 748–760, 2013—Commercial high-intensity, short rest (HI/SR) protocols have been anecdotally postured to be extremely demanding. However, limited prior studies have demonstrated HI/SR protocols to produce hyperreactions in metabolic and adrenal function; thus, the purpose of this study was to evaluate the physiological effects of an acute, high-intensity (75% 1-repetition maximum), short rest resistance exercise protocol. Nine trained men (age: 23.5 ± 3.5 years, height: 172.4 ± 4.0 cm, weight: 77.8 ± 8.8 kg) and 9 trained women (age: 22.9 ± 2.0 years, height: 168.4 ± 9.4 cm, weight: 68.5 ± 10.4 kg) participated in the HI/SR protocol, which consisted of a descending pyramid scheme of back squat, bench press, and deadlift, beginning with 10 repetitions of each, then 9, then 8, and so on until 1 repetition on the final set. Significant time effects were observed in lactate (immediate post [IP], +15, +60) and cortisol (IP, +15, +60) response. Significant sex effects were observed in lactate response (IP, +15) but not in cortisol response. Total work was higher in men and influenced magnitude of increase in lactate but not cortisol. No significant sex differences were noted in time to completion, average relative intensity, heart rate response or rating of perceived exertion scores. Highest lactate (IP men: 17.3 mmol·L−1; IP women: 13.8 mmol·L−1) and cortisol (+15 men: 1,860.2 nmol·L−1; +15 women: 1,831.7 nmol·L−1) values were considerably greater than those produced in typical resistance exercise programs, confirming that relative intensity and rest period length are important factors determining magnitude of metabolic and adrenal stress. Practical applications for the coach include cautious implementation of HI/SR protocols, as long-term sequential use may promote overtraining. A gradual reduction in rest interval length with concurrent gradual increase in intensity should be used to minimize potential negative effects such as nonfunctional overreaching.

Effects of resistance training fatigue on joint biomechanics.

Abstract Hooper, DR, Szivak, TK, DiStefano, LJ, Comstock, BA, Dunn-Lewis, C, Apicella, JM, Kelly, NA, Creighton, BC, Volek, JS, Maresh, CM, and Kraemer, WJ. Effects of resistance training fatigue on joint biomechanics. J Strength Cond Res 27(1): 146–153, 2013—Resistance training has been found to have a multitude of benefits. However, when performed with short rest, resistance training can result in substantial fatigue, which may have a negative impact on exercise technique. The purpose of this study is to examine the effects of fatigue from resistance exercise on joint biomechanics to determine what residual movement effects may exist after the workout. Twelve men with at least 6 months of resistance training experience (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg) performed 5 body weight squats before (pretest) and after (posttest) a highly fatiguing resistance training workout. Lower extremity biomechanics were assessed using a 3-dimensional motion analysis system during these squats. Peak angle, total displacement, and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation, and hip adduction. Results showed a significant decrease in peak angle for knee flexion (Pre: 120.28 ± 11.93°, Post: 104.46 ± 9.85°), hip flexion (Pre: −109.42 ± 12.49°, Post: −95.8 ± 12.30°), and hip adduction (Pre: −23.32 ± 7.04°, Post: −17.30 ± 8.79°). There was a significant reduction in angular displacement for knee flexion (Pre: 115.56 ± 10.55°, Post: 103.35 ± 10.49°), hip flexion (Pre: 97.94 ± 10.69°, Post: 90.51 ± 13.22°), hip adduction (Pre: 17.79 ± 7.36°, Post: 11.89 ± 4.34°), and hip rotation (Pre: 30.72 ± 12.28, Post: 20.48 ± 10.12). There was also a significant reduction in displacement rate for knee flexion (Pre: 2.20 ± 0.20, Post: 1.98 ± 0.20), hip flexion (Pre: 1.92 ± 0.20, Post: 1.76 ± 0.27), hip adduction (Pre: −0.44 ± 0.17, Post: −0.31 ± 0.17), and hip rotation (Pre: 0.59 ± 0.23, Post: 0.38 ± 0.21). This study demonstrated that there are lasting residual effects on movement capabilities after a high-intensity short rest protocol. Thus, strength and conditioning coaches must be careful to monitor movements and exercise techniques after such workouts to prevent injury and optimize subsequent exercise protocols that might be sequenced in order.

A multi-nutrient supplement reduced markers of inflammation and improved physical performance in active individuals of middle to older age: a randomized, double-blind, placebo-controlled study

BackgroundWhile exercise acts to combat inflammation and aging, the ability to exercise may itself be compromised by inflammation and inflammations impact on muscle recovery and joint inflammation. A number of nutritional supplements have been shown to reduce inflammation and improve recovery. The purpose of the current investigation was to examine the effect of a multi-nutrient supplement containing branched chain amino acids, taurine, anti-inflammatory plant extracts, and B vitamins on inflammatory status, endothelial function, physical function, and mood in middle-aged individuals.MethodsThirty-one healthy and active men (N = 16, mean age 56 ± 6.0 yrs) and women (N = 15, mean age = 52 ± 7.5 yrs) participated in this investigation. Subjects completed one 28 day cycle of placebo supplementation and one 28 day cycle of multi-nutrient supplementation (separated by a one week washout period) in a balanced, randomized, double-blind, cross-over design. Subjects completed weekly perceptual logs (PROMIS-57, KOOS) and pre- and post- testing around the supplementation period. Testing consisted of brachial artery flow mediated dilation (FMD), blood measures, and physical performance on vertical jump, handgrip strength, and balance (dispersion from center of pressure). Significance for the investigation was p ≤ 0.05.ResultsIL-6 significantly decreased in both men (from 1.2 ± 0.2 to 0.7 ± 0.4 pg·mL-1) and women (from 1.16 ± 0.04 to 0.7 ± 0.4 pg·mL-1). Perceived energy also improved for both men (placebo: 1.8 ± 0.7; supplement: 3.7 ± 0.8 AUC) and women (placebo: 1.2 ± 0.7; supplement: 2.8 ± 0.8 AUC). Alpha-1-antichymotrypsin (from 108.9 ± 38.6 to 55.5 ± 22.2 ug·mL-1), Creatine Kinase (from 96 ± 34 to 67 ± 23 IU·L-1), general pain, and joint pain decreased in men only, while anxiety and balance (from 0.52 ± 0.13 to 0.45 ± 0.12 cm) improved in women only. Men showed increased performance in vertical jump power (from 2642 ± 244 to 3134 ± 282 W) and grip strength (from 42.1 ± 5.9 to 48.5 ± 4.9 kg).ConclusionsA multi-nutrient supplement is effective in improving inflammatory status in both men and women, markers of pain, joint pain, strength, and power in men only, and both anxiety and balance (a risk factor for hip fracture) in women. Therefore, a multi-nutrient supplement may help middle-aged individuals to prolong physical function and maintain a healthy, active lifestyle.

Influence of HMB supplementation and resistance training on cytokine responses to resistance exercise

Purpose: The purpose of this study was to determine the effects of a multinutritional supplement including amino acids, β-hydroxy-β-methylbutyrate (HMB), and carbohydrates on cytokine responses to resistance exercise and training. Methods: Seventeen healthy, college-aged men were randomly assigned to a Muscle Armor™ (MA; Abbott Nutrition, Columbus, OH) or placebo supplement group and 12 weeks of resistance training. An acute resistance exercise protocol was administered at 0, 6, and 12 weeks of training. Venous blood samples at pre-, immediately post-, and 30-minutes postexercise were analyzed via bead multiplex immunoassay for 17 cytokines. Results: After 12 weeks of training, the MA group exhibited decreased interferon-gamma (IFN-γ) and interleukin (IL)-10. IL-1β differed by group at various times. Granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, IL-7, IL-8, IL-12p70, IL-13, IL-17, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1 beta (MIP-1β) changed over the 12-week training period but did not differ by group. Conclusions: Twelve weeks of resistance training alters the cytokine response to acute resistance exercise, and supplementation with HMB and amino acids appears to further augment this result.

Changes in creatine kinase and cortisol in National Collegiate Athletic Association Division I American football players during a season.

Abstract Kraemer, WJ, Looney, DP, Martin, GJ, Ratamess, NA, Vingren, JL, French, DN, Hatfield, DL, Fragala, MS, Spiering, BA, Howard, RL, Cortis, C, Szivak, TK, Comstock, BA, Dunn-Lewis, C, Hooper, DR, Flanagan, SD, Volek, JS, Anderson, JM, Maresh, CM, and Fleck, SJ. Changes in creatine kinase and cortisol in national collegiate athletic association division I American football players during a season. J Strength Cond Res 27(2): 434–441, 2013—The purpose of this study was to track creatine kinase (CK) and serum cortisol over an American college football season starting with the preseason practice. A secondary purpose was to observe changes in basic clinical chemistries. Twenty-two National Collegiate Athletic Association Division I football players (age: 20.4 ± 1.1 years, height: 188.27 ± 8.3 cm, weight: 115.8 ± 29.7 kg) volunteered to participate in this study. Each of the players had participated in the summer strength and conditioning supervised program. Resting blood samples were obtained just before the start of preseason practice (T-1), 2 weeks later (T-2), and the day after game 2 (T-3), game 4 (T-4), game 6 (T-5), and game 9 (T-6) of a 12-game season. Creatine kinase, a panel of clinical chemistries, cortisol, and testosterone were assayed at each time point. No significant changes in CK concentrations were observed over the season with peak values of each range ⩽1,070.0 IU·L−1, but the largest range was observed at T-6 after game 9 (119–2,834 IU·L−1. The analysis of covariance analysis demonstrated that the number of plays in the ninth game (T-6) explained the magnitude of the changes in CK. No changes in serum cortisol concentrations were observed yet, again large variations existed with peak values of each range ⩽465.0 nmol·L−1. Clinical chemistries showed various significant changes from T-1, but none were considered clinically relevant changes for any player over the time course of the study. In conclusion, the strength and conditioning program before preseason camp or the structure of summer camp practices and the in-season strength and conditioning appeared to mute muscle damage and the stress response of cortisol. Such data demonstrate that changes in muscle damage and adrenal cortical stress over the season are minimal, yet large individual variations can be observed. Management of these variables appears to be related to optimal strength and conditioning and sports medicine programs. Thus, the greater concerns for student-athlete safety in the sport of American football are related to preventing sudden death, traumatic injury, and managing concussion syndromes.

Resistance exercise induces region-specific adaptations in anterior pituitary gland structure and function in rats

The anterior pituitary gland (AP) increases growth hormone (GH) secretion in response to resistance exercise (RE), but the nature of AP adaptations to RE is unknown. To that end, we examined the effects of RE on regional AP somatotroph GH release, structure, and relative quantity. Thirty-six Sprague-Dawley rats were assigned to one of four groups: 1) no training or acute exercise (NT-NEX); 2) no training with acute exercise (NT-EX); 3) resistance training without acute exercise (RT-NEX); 4) resistance training with acute exercise (RT-EX). RE incorporated 10, 1 m-weighted ladder climbs at an 85° angle. RT groups trained 3 days/wk for 7 wk, progressively. After death, trunk blood was collected, and each AP was divided into quadrants (ventral-dorsal and left-right). We measured: 1) trunk plasma GH; 2) somatotroph GH release; 3) somatotroph size; 4) somatotroph secretory content; and 5) percent of AP cells identified as somatotrophs. Trunk GH differed by group (NT-NEX, 8.9 ± 2.4 μg/l; RT-NEX, 9.2 ± 3.5 μg/l; NT-EX, 15.6 ± 3.4 μg/l; RT-EX, 23.4 ± 4.6 μg/l). RT-EX demonstrated greater somatotroph GH release than all other groups, predominantly in ventral regions (P < 0.05-0.10). Ventral somatotrophs were larger in NT-EX and RT-NEX compared with RT-EX (P < 0.05-0.10). RT-NEX exhibited significantly greater secretory granule content than all other groups but in the ventral-right region only (P < 0.05-0.10). Our findings indicate reproducible patterns of spatially distinct, functionally different somatotroph subpopulations in the rat pituitary gland. RE training appears to induce dynamic adaptations in somatotroph structure and function.