Abstract
BackgroundBetaine supplementation has been shown to improve body composition and some metrics of muscular performance in young men; but, whether betaine enhances body composition or performance in female subjects is currently unknown. Therefore, the purpose of this study was to investigate the interaction between resistance training adaptation and chronic betaine supplementation in females.MethodsTwenty-three young women (21.0 ± 1.4 years, 165.9 ± 6.4 cm, 68.6 ± 11.8 kg) without prior structured resistance training experience volunteered for this study. Body composition (BodPod), rectus femoris muscle thickness (B-mode Ultrasound), vertical jump, back squat 1RM and bench press 1RM were assessed pre- and post-training. Following 1 week of familiarization training, subjects were matched for body composition and squat strength, and randomly assigned to either a betaine (2.5 g/day; n = 11) or placebo (n = 12) group that completed 3 sets of 6–7 exercises per day performed to momentary muscular failure. Training was divided into two lower and one upper body training sessions per week performed on non-consecutive days for 8 weeks, and weekly volume load was used to analyze work capacity.ResultsSignificant main effects of time were found for changes in lean mass (2.4 ± 1.8 kg), muscle thickness (0.13 ± 0.08 cm), vertical jump (1.8 ± 1.6 cm), squat 1RM (39.8 ± 14.0 kg), and bench press 1 RM (9.1 ± 7.3 kg); however, there were no significant interactions. A trend (p = .056) was found for greater weekly training volumes for betaine versus placebo. Significant interactions were found for changes in body fat percentage and fat mass: body fat percentage and fat mass decreased significantly more in betaine (− 3.3 ± 1.7%; − 2.0 ± 1.1 kg) compared to placebo (− 1.7 ± 1.6%; − 0.8 ± 1.3 kg), respectively.ConclusionsThe results of this study indicated that betaine supplementation may enhance reductions in fat mass, but not absolute strength, that accompany a resistance training program in untrained collegiate females.
Highlights
Betaine supplementation has been shown to improve body composition and some metrics of muscular performance in young men; but, whether betaine enhances body composition or performance in female subjects is currently unknown
While strength-endurance was not tested in the present study, a trend for greater total weekly volumes was found, with effect sizes favoring the betaine group in 4 of the 7 weeks as well as overall. These results are in agreement with our previous study, where we found betaine supplementation increased bench press work capacity in trained men only during the higher volume meso-cycles [7], and lend evidence to the hypothesis that betaine may be most ergogenic during higher volume resistance training protocols
In summary, the major findings of the present study are that 9 weeks of betaine supplementation improved body composition by reducing fat mass and tended to improve high-volume work capacity, but not strength or power performance in young, active, resistance training naïve females
Summary
Betaine supplementation has been shown to improve body composition and some metrics of muscular performance in young men; but, whether betaine enhances body composition or performance in female subjects is currently unknown. Hoffman et al [9] demonstrated improved squat repetitions to fatigue, but not bench press throw or vertical jump with 15 days of 2.5 g/day betaine supplementation; a later study by Hoffman et al [10] reported no improvements in isokinetic force output following an identical supplementation protocol. Unlike Hoffman et al [10], the subjects in Cholewa et al [7] and Lee et al [11] were assigned standardized resistance training between testing sessions. These studies provide evidence that indicates betaine supplementation may be effective in improving muscular performance when accompanied by structured resistance training
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