Michael P. Godard

β-hydroxy-β-methylbutyrate ingestion, Part I : effects on strength and fat free mass

PURPOSE The purpose of this investigation was 1) to determine whether HMB supplementation results in an increase in strength and FFM during 8 wk of resistance training and 2) determine whether a higher dose of HMB provides additional benefits. METHODS Thirty-seven, untrained, college-aged men were assigned to one of three groups: 0, 38, or 76 mg x kg(-1) x d(-1) of HMB (approximately equal to 3 and 6 g x d(-1), respectively). Resistance training consisted of 10 different exercises performed 3 d x wk(-1) for 8 wk at 80% of 1-repetition maximum (1RM). The 1RM was reevaluated every 2 wk with workloads adjusted accordingly. RESULTS No differences were observed in 1RM strength among the groups at any time. However, the 38 mg x kg (-1) x d(-1) group showed a greater increase in peak isometric torque than the 0 or 76 mg.kg(-1) x d(-1) groups (P < 0.05). The 76 mg x kg(-1) x d(-1) group had a greater increase in peak isokinetic torque than the 0 or 38 mg x kg(-1) x d(-1) groups at 2.1, -3.15, and -4.2 rad x s(-1) (P < 0.05). Plasma creatine phosphokinase (CPK) activity was greater for the 0 mg x kg(-1) x d(-1) versus the 38 or 76 mg x kg(-1) x d(-1) groups at 48 h after the initial training bout (P < 0.05). In addition, no differences were observed in body fat between the three groups. However, the 38 mg x kg(-1) x d(-1) group exhibited a greater increase in FFM (P < 0.05). CONCLUSIONS Although the IRM strength gains were not significantly different, HMB supplementation appears to increase peak isometric and various isokinetic torque values, and increase FFM and decrease plasma CPK activity. Lastly, it appears that higher doses of HMB (i.e., > 38 mg x kg(-1) x d(-1)) do not promote strength or FFM gains.

The effects of varied rest periods between sets to failure using the bench press in recreationally trained men.

The purpose of this study was to determine the rate of recovery for recreational weight trainers between 2 sets of bench press to volitional exhaustion. Twenty-eight men performed 2 sets of the bench press at 75% of their previously determined 1 repetition maximum (1RM) to volitional exhaustion. Rest periods of 1, 3, or 5 minutes between sets were utilized on the 3 separate testing days. There was a significant decrease in the number of repetitions performed between the second sets at all rest periods. There were no significant differences in work performed (repetitions × weight) during the second set with the 3- and 5-minute rest periods, but the total work with a 1-minute rest period (1,389.1 ± 529.9) was significantly less than both the 3- (1,494.9 ± 451.0) and 5-minute (1,711.4 ± 478.0) rest period. The data indicated that subjects were unable to fully recover between the first and second sets of maximal resistance exercise, regardless of the rest period. However, subjects were able to maintain a performance level of 8–12 repetitions and sustain the total work performed per set with as little as 3 minutes rest between sets.

β-hydroxy-β-methylbutyrate ingestion, Part II : effects on hematology, hepatic and renal function

PURPOSE The purpose of this investigation was to examine the effects of differing amounts of beta-hydroxy-beta-methylbutyrate (HMB), 0, 36, and 76 mg x kg(-1) x d(-1), on hematology, hepatic and renal function during 8 wk of resistance training. METHODS Thirty-seven, untrained collegiate males and were randomly assigned to one of the three groups, 0, 38, or 76 mg x kg(-1) x d(-1). Resistance training consisted of 10 exercises, performed 3 d x wk(-1) for 8 wk at 80% of their 1-repetition maximum. Blood and urine was obtained before training, 48 h after the initial session, 1 wk, 2 wk, 4 wk, and at 8 wk of resistance training. Blood was analyzed for glucose, blood urea nitrogen, hemoglobin, hepatic enzymes, lipid profile, total leukocytes, and individual leukocytes. Urine was analyzed for pH, glucose, and protein excretion. RESULTS The 38 mg x kg(-1) x d(-1) group had a greater increase in basophils compared with 0 or 76 mg x kg(-1) x d(-1) groups (P < 0.05). No difference occurred in any other blood and urine measurements. CONCLUSION These data indicate that 8 wk of HMB supplementation (< or = 76 mg x kg(-1) x d(-1)) during resistance training had no adverse affects on hepatic enzyme function, lipid profile, renal function, or the immune system.

Insulin-like growth factor I-mediated skeletal muscle hypertrophy is characterized by increased mTOR-p70S6K signaling without increased Akt phosphorylation

Background Insulin-like growth factor I (IGF-I) is an anabolic hormone that is known to induce skeletal muscle hypertrophy. However, the signaling pathways mediating IGF-Is hypertrophic effect in vivo are unknown. Method The phosphorylation of 46 proteins was investigated by Kinetworks proteomic analysis in the gastrocnemius muscle of transgenic mice overexpressing IGF-I myosin light chain/muscle specific IGF-I (MLC/mIgf-I) and wild-type littermates. Results In the hypertrophic muscle of MLC/mIgf-I mice, we observed increased phosphorylation of phosphoinositide-dependent protein kinase 1 (PDK1; 53% increase), the mammalian target of rapamycin (mTOR; 112% increase), and p70 S6 kinase (p70S6K) (254% increase) but no significant change in Akt phosphorylation (4% decrease). Furthermore, we found reduced phosphorylation of MAP kinase kinase 1 and 2 (MEK1/2) (60% decrease) and of mitogen-activated protein kinase kinases 3 and 6 (MKK3/6) (50% decrease) in muscle from transgenic mice, suggesting that the hypertrophic and mitogenic effects of IGF-I are mediated via distinct signaling pathways in skeletal muscle and that inhibition of the mitogen-activated protein (MAP) kinase pathway may be required for the IGF-I-induced hypertrophic effect. Single-fiber analysis revealed a trend toward a higher percentage of the fast twitch fibers (IIb and IIx) in the transgenic mice. Conclusion Persistent overexpression of IGF-I in mice skeletal muscle results in hypertrophy, which is likely mediated via the mTOR/p70S6K pathway, potentially via an Akt-independent signaling pathway.

Oral amino-acid provision does not affect muscle strength or size gains in older men.

PURPOSE The intent of this investigation was to examine the effects of a daily oral provision consisting of amino acids (L-lysine, L-leucine, L-valine, L-phenylalanine, L-threonine, L-histidine, L-isoleucine, and L-methionine) in combination with carbohydrates (dextrose, sucrose, and fructose) on whole muscle strength and size characteristics during a 12-wk progressive knee extensor resistance training (PRT) program in older men (>65 yr). METHODS Seventeen older men were randomly assigned to either the experimental (EX) or control (CN) groups. The EX (N = 8) and CN (N = 9) groups had the following characteristics-EX: 70.8 +/- 1.5 yr, 91.0 +/- 4.9 kg, and 177.0 +/- 3.9 cm; CN: 72.1 +/- 1.9 yr, 75.4 +/- 4.7 kg, and 176.1 +/- 3.0. Pre and post PRT maximal unilateral isometric torque (N.m), isokinetic torque (1.05, 1.57, 2.09, 3.14, 4.19, and 5.24 rad.s-1), work capacity (30 consecutive reps at 3.14 rad.s-1) torque, one repetition maximum (1RM) bilateral isotonic strength, and whole muscle cross-sectional area (CSA) of the mid-thigh were performed by computed tomography on each subject. RESULTS All variables showed an improvement with training (P < 0.05); however, there were no differences between the groups. Both groups increased in isometric strength by 21%, and isokinetic torque by 24% to 11% with the varying velocities (1.05-5.24 rad.s-1). Whole muscle 1RM strength and thigh CSA increased 50% and 6.5%, respectively. Additionally, voluntary torque/CSA increased 12% in both the EX and CN groups (P < 0.05). CONCLUSIONS In conclusion, these data suggest that whole muscle strength and size are not enhanced with a postexercise daily provision of an oral amino-acid complex during 12 wk of PRT in older men.

Validating Inbody® 570 Multi-frequency Bioelectrical Impedance Analyzer versus Dxa for Body Fat Percentage Analysis.: 3576 Board #15 June 4, 8

Miller RM, Chambers TL, Burns SP. Validating InBody® 570 Multifrequency Bioelectrical Impedance Analyzer versus DXA for Body Fat Percentage Analysis. JEPonline 2016;19(5):71-78. The aim of this investigation was to evaluate the relation between body fat percentages determined by dual-energy x-ray absorptiometry (DXA) versus multi-frequency bioelectrical impedance analysis (MfBIA). One hundred and ten recreationally active individuals (72 male, 38 female) completed a 12-hr fast, refrained from exercise for a minimum of 12 hrs, and alcohol consumption 24 hrs prior to testing. After anthropometric measures were assessed, the subjects’ body fat percentage was determined from DXA and MfBIA subsequently. Each subject completed both body composition assessments in one visit to the Human Performance Laboratory. Pearson’s correlations and paired t tests were computed for fat tissue percentage from DXA and MfBIA. Subjects’ mean age, height, and weight were 20.72 ± 2 yrs, 174.61 ± 10.09 cm, and 77.94 ± 17.76 kg, respectively. Body fat percentages between the DXA (25.61 ± 10.56%) and MfBIA (20.99 ± 9.34%) were significantly related (r =.94, P<0.0001). Body fat percentage determined by DXA shares 88% of the variance with MfBIA, leaving 12% variance unexplained. However, the t tests displayed significant differences between modalities for each group comparison (P<0.0001). The results of the current study reveal if strict guidelines are adhered to MfBIA is a comparable method for determining body fat percentage when compared to DXA.

MAINTENANCE OF WHOLE MUSCLE STRENGTH AND SIZE FOLLOWING RESISTANCE TRAINING IN OLDER MEN

Following a progressive resistance training (PRT) program of 3 days per week, we sought to examine how effective a resistance training maintenance program of 1 day per week would be to preserve muscle strength and size in older men. Each subjects whole muscle strength (1 repetition maximum, or 1RM) and whole muscle size (determined by computed tomography scan) were measured before (T1) and after (T2) 12 weeks of PRT and again following 6 months (T3) of training (TR) or detraining (DT). During the 12-week PRT, older men (N = 10; age 70 +/- 4 years) trained their knee extensors 3 days per week at 80% of their 1RM. The maintenance program consisted of older men (n = 5; TR; 75 +/- 1 years) who completed 3 sets of 10 repetitions at 80% of their 1RM 1 day per week (this was equivalent to a single training session that was performed 3 days per week during the 12-week PRT). The other group of older men (n = 5; DT; 69 +/- 1 years) resumed their normal lifestyle (no regular physical activity) following the 12-week PRT. From T1 to T2, muscle strength increased (p <.05) 45% (66 +/- 10 to 94 +/- 10 kg) in the TR group and 53% (50 +/- 6 to 74 +/- 7 kg) in the DT group. From T2 to T3, whole muscle strength of the TR group was unchanged (96 +/- 11 kg), whereas strength decreased (p <.05) in the DT group by 11% (66 +/- 6 kg). Muscle size demonstrated a similar pattern with a 7% increase (p <.05) in both groups from T1 to T2. No change in muscle size was found in the TR group from T2 to T3, whereas the DT group had a 5% reduction (p <.05). These data indicate that resistance training 1 day per week was sufficient to maintain muscle strength and size in these older men following a 12-week PRT program. Furthermore, the men who resumed their normal lifestyle (no regular physical activity) experienced significant losses in muscle strength and size.

Antioxidants and Recovery from Exercise Induced Muscle Damage: 246 Board #83 June 1, 9: 30 AM - 11: 00 AM.

by Kara A. Stone Recent research suggests that ingesting antioxidants during training may reduce exercise induced muscle soreness (EIMD), therefore the purpose of this study is to examine the effect of antioxidant supplementation on the performance related symptoms of EIMD in female participants. Methods: Participants were 10 non-resistance trained females, 21.6 ± 2.8 years. Subjects underwent 12 days of supplementation with an antioxidant capsule and 12 days of supplementation with a placebo capsule. To induce muscle damage, subjects performed an eccentric leg press protocol followed by measurements for range of motion (ROM), resting blood lactate, 5-RM testing, Wingate power output testing, and perceived muscle soreness. Assessments occurred prior to supplementation, immediately after exercise protocol, 48 and 96 hours post-exercise. Results: There were no significant changes in ROM, resting blood lactate, muscular strength, power output, or perceived muscle soreness between trials over the 96 hours following the exercise protocol. Conclusion: Antioxidant supplementation appears to have no effect on the performance related symptoms of EIMD in female participants. ANTIOXIDANTS AND RECOVERY FROM EXERCISE INDUCED MUSCLE DAMAGE. Kara A. Stone The University of Central Missouri A Thesis presented in partial fulfillment of the requirements for the degree of Master of Exercise Science in the Department of Nutrition and Kinesiology University of Central Missouri August, 2015