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

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Abstract

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·kg-1·d-1 of HMB (approximately equal to 3 and 6 g·d-1, respectively). Resistance training consisted of 10 different exercises performed 3 d·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·kg-1·d-1 group showed a greater increase in peak isometric torque than the 0 or 76 mg·kg-1·d-1 groups (P < 0.05). The 76 mg·kg-1·d-1 group had a greater increase in peak isokinetic torque than the 0 or 38 mg·kg-1·d-1 groups at 2.1, −3.15, and −4.2 rad·s-1 (P < 0.05). Plasma creatine phosphokinase (CPK) activity was greater for the 0 mg·kg-1·d-1 versus the 38 or 76 mg·kg-1·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·kg-1·d-1 group exhibited a greater increase in FFM (P < 0.05).

Conclusions:

Although the 1RM 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·kg-1·d-1) do not promote strength or FFM gains.

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