Austin D. Thrower

The Acute Response of Practical Occlusion in the Knee Extensors

Loenneke, JP, Kearney, ML, Thrower, AD, Collins, S, and Pujol, TJ. The acute response of practical occlusion in the knee extensors. J Strength Cond Res 24(10): 2831-2834, 2010-Training at low intensities with moderate vascular occlusion results in increased muscle hypertrophy, strength, and endurance. Elastic knee wraps, applied to the proximal portion of the target muscle, might elicit a stimulus similar to the KAATSU Master Apparatus. The purpose of this study was to test the hypothesis that intermittently occluding the leg extensors with elastic knee wraps would increase whole-blood lactate (WBL) over control (CON). Twelve healthy men and women participated in this study (age 21.2 ± 0.35 years, height 168.9 ± 2.60 cm, and body mass 71.2 ± 4.16 kg). One repetition maximum (1RM) testing for the leg extensors was performed on a leg extension machine for the first trial, followed by occlusion (OCC) and CON trials. Four sets of leg extension exercise (30-15-15-15) were completed with 150-second rest between sets at 30% 1RM. Whole-blood lactate, heart rate (HR), and ratings of perceived exertion (RPEs) were measured after every set of exercise and 3 minutes postexercise. Data were analyzed using repeated-measures analysis of variance with statistical significance set at p ≤ 0.05. Whole-blood lactate increased in response to exercise (p = 0.01) but was not different between groups (OCC 6.28 ± 0.66 vs. CON 5.35 ± 0.36 mmol·L−1, p = 0.051). Heart rate (OCC 128.86 ± 4.37 vs. CON 119.72 ± 4.10 b·min−1) was higher with OCC from sets 2-4 (p ≤ 0.03), with no difference 3 minutes postexercise (p = 0.29). Rating of perceived exertion was higher with OCC after every set (OCC 15.10 ± 0.31 vs. CON 12.16 ± 0.50, p = 0.01). In conclusion, no differences exist for WBL between groups, although there was a trend for higher levels with OCC. The current protocol for practical occlusion did not significantly increase metabolic stress more than normal low-intensity exercise. This study does not support the use of knee wraps as a mode of blood-flow restriction.

Blood flow restriction reduces time to muscular failure

Abstract Exercise to failure results in similar muscle protein synthesis responses, independent of intensity. However, low-intensity exercise likely requires more repetitions and individuals with injuries may be incapable of sustaining the mechanical stress to reach failure. The aim of this study was to determine if knee wraps provide a stimulus to decrease time to failure. Twenty healthy individuals participated in a randomized crossover study consisting of three trials. The first trial was used to determine one-repetition maximum (1-RM) on leg extension. Participants were then assigned to a blood flow restriction or control group. After trial 2, participants crossed over to the opposite trial. Knee wraps were placed around the upper thigh of each leg during blood flow restriction. Leg extensions were completed at 30% 1-RM until failure. A rating of perceived exertion was taken after exercise and whole blood samples were taken before, after, and 3 min after exercise for the determination of lactate. Repetitions until failure and total work were significantly lower with practical blood flow restriction compared with the control trial. Metabolic stress as measured by whole blood lactate was higher immediately after muscular failure in the control compared with the blood flow restriction trial, but not so 3 min after exercise. There were no differences in ratings of perceived exertion. In conclusion, knee wraps provide a stimulus for blood flow restriction allowing failure to occur sooner with similar metabolic stress after reperfusion. However, similar perceptual responses despite the lower workload with blood flow restriction may limit its application to the highly motivated.

Short Report: Relationship between Quality Protein, Lean Mass and Bone Health

Background: Quality protein intake, and distribution of that protein, could play an important role with lean mass (LM), bone mineral density (BMD) and bone mineral content (BMC). Research has demonstrated that muscle protein synthesis is maximally stimulated at approximately 10 g of essential amino acids (EAA)/meal. This study sought to determine the relationship between the amount of quality protein consumed and the amount of times the approximately 10 g EAA threshold was reached at a meal, with respect to LM, BMD and BMC. Methods: Twenty-seven subjects participated in this study. EAA intake was determined from a 3-day food record, and amino acid profiling was determined using a computer program (USDA Database, release 22). LM, BMD and BMC were measured using dual-energy X-ray absorptiometry. Quality protein was defined as the ratio of EAA to total dietary protein. Data were analyzed using Pearson partial coefficient correlations, controlling for body mass, with an α-level of 0.05. Results: Quality protein consumed in a 24-hour period and the amount of times reaching the EAA threshold per day was positively associated with LM, BMD and BMC, and had an inverse relationship with body fat percentage. Conclusion: Both quality protein intake and frequency are positively associated with favorable body composition and bone health.

The relationship between quality protein, lean mass, and bone health

Background The amount of quality protein (Essential Amino Acids (EAA): Protein) intake, and distribution of that protein to a meal, could play an important role with regard to lean mass (LM), bone mineral density (BMD), and bone mineral content (BMC). Research has demonstrated that muscle protein synthesis (MPS) is maximally stimulated at ~10g of EAA per meal (Cuthbertson, et al. 2005). A cross sectional study sought to determine the relationship between the amount of quality protein consumed in 24 hours and the amount of times the ~10g EAA threshold was reached at a meal, with respect to LM, BMD, and BMC.

Contents Vol. 57, 2010

F. Azizi, Tehran A. Berg, Freiburg F. Branca, Rome R. Brigelius-Flohé, Nuthetal P.C. Calder, Southampton N. Chang, Seoul T. Decsi, Pécs K. Eder, Halle/Saale A. El-Sohemy, Toronto, Ont. H. Goldenberg, Vienna R. Hakkak, Little Rock, Ark. H. Hauner, Munich S. Hercberg, Paris H. Heseker, Paderborn N. Houalla, Beirut A. Kafatos, Heraklion M.-H. Kang, Daejeon E.T. Kennedy, Boston, Mass. M. Krawinkel, Giessen G. Krejs, Graz A.V. Kurpad, Bangalore W. Langhans, Zurich M. Lawrence, Burwood, Vic. D. Li, Hangzhou X. Lin, Shanghai J. Linseisen, Heidelberg J.A. Martinez, Pamplona Y. Naito, Kyoto H.Y. Paik, Seoul M. Panagiotidis, Reno, Nev. J.M. Pettifor, Johannesburg L.A. Réthy, Budapest G. Rimbach, Kiel J. Sabaté, Loma Linda, Calif. W.H.M. Saris, Maastricht L. Serra-Majem, Las Palmas de Gran Canaria A.P. Simopoulos, Washington, D.C. P. Stehle, Bonn J.J. Strain, Coleraine I. Th orsdottir, Reykjavik K. Tontisirin, Nakhon Pathom R. Uauy, Santiago H. Vannucchi, Ribeirão Preto A. von Rücker, Bonn M. Wahlqvist, Clayton W. Waldhäusl, Vienna E. Wasantwisut, Salaya B. Watzl, Karlsruhe W.M. Windisch, Vienna T. Yoshikawa, Kyoto J. Zempleni, Lincoln, Nebr. A. Zittermann, Bad Oeynhausen Journal of Nutrition, Metabolic Diseases and Dietetics