Postexercise Muscle Glycogen Recovery Enhanced with a Carbohydrate-Protein Supplement

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Abstract

Purpose:

This study assessed whether liquid carbohydrate-protein (C + P) supplements, ingested early during recovery, enhance muscle glycogen resynthesis versus isoenergetic liquid carbohydrate (CHO) supplements, given early or an isoenergetic solid meal given later during recovery (PLB).

Methods:

Two hours after breakfast (7.0 kcal·kg−1; 0.3 g·kg−1 P, 1.2 g·kg−1 C, 0.1 g·kg−1 F), six male cyclists performed a 60-min time trial (AMex). Pre- and postexercise, vastus lateralis glycogen concentrations were determined using nMRS. Immediately, 1 h, and 2 h postexercise, participants ingested C + P (4.8 kcal·kg−1; 0.8 g·kg−1 C, 0.4 g·kg−1 P), CHO (4.8 kcal·kg−1; 1.2 g·kg−1 C), or PLB (no energy). Four hours postexercise, a solid meal was ingested. At that time, C + P and CHO received a meal identical to breakfast, whereas PLB received 21 kcal·kg−1 (1 g·kg−1 P, 3.6 g·kg−1 C, 0.3 g·kg−1 F); energy intake during 6 h of recovery was identical among treatments. After 6 h of recovery, measurement and cycling protocols (PMex) were repeated.

Results:

Absolute muscle glycogen utilization was 18% greater (P ≤ 0.05) during AMex (C + P: −42.75 ± 5.24 mmol·L−1; CHO: −37.08 ± 7.59 mmol·L−1; PLB: −53.78 ± 11.59 mmol·L−1; P = 0.302) relative to PMex (C + P: −38.40 ± 4.37 mmol·L−1; CHO: −31.16 ± 3.78 mmol·L−1; PLB: −40.33 ± 1.47 mmol·L−1; P = 0.292), but there were no differences between groups. During 6 h of recovery, muscle glycogen resynthesis was greater in C + P (+ 28.62 ± 2.10 mmol·L−1) versus CHO (+ 22.20 ± 1.19 mmol·L−1, P ≤ 0.05) or PLB (+ 18.50 ± 7.67 mmol·L−1, P ≤ 0.05). Cycling performance was similiar (P = 0.282) among treatments during both AMex (C + P: 37.61 ± 0.63 km; CHO: 37.03 ± 0.60 km; PLB: 37.24 ± 0.34 km) and PMex (C + P: 36.31 ± 0.83 km; CHO: 36.38 ± 0.80 km; PLB: 35.34 ± 0.45 km).

Conclusions:

C + P supplements, given early after exercise, enhance glycogen resynthesis relative to CHO and PLB. However, this does not influence performance in this type of exercise bout.

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