Recovery from a cycling time trial is enhanced with carbohydrate-protein supplementation vs. isoenergetic carbohydrate supplementation

Abstract

Background: In this study we assessed whether a liquid carbohydrate-protein (C+P) supplement (0.8 g/kg C; 0.4 g/kg P) ingested early during recovery from a cycling time trial could enhance a subsequent 60 min effort on the same day vs. an isoenergetic liquid carbohydrate (CHO) supplement (1.2 g/kg).

Methods: Two hours after a standardized breakfast, 15 trained male cyclists completed a time trial in which they cycled as far as they could in 60 min (AM(ex)) using a Computrainer indoor trainer. Following AM(ex), subjects ingested either C+P, or CHO at 10, 60 and 120 min, followed by a standardized meal at 4 h post exercise. At 6 h post AM(ex) subjects repeated the time trial (PM(ex)).

Results: There was a significant reduction in performance for both groups in PM(ex) versus AM(ex). However, performance and power decreases between PM(ex) and AM(ex) were significantly greater (p </= 0.05) with CHO (-1.05 +/- 0.44 km and -16.50 +/- 6.74 W) vs C+P (-0.30 +/- 0.50 km and -3.86 +/- 6.47 W). Fat oxidation estimated from RER values was significantly greater (p </= 0.05) in the C+P vs CHO during the PM(ex), despite a higher average workload in the C+P group.

Conclusion: Under these experimental conditions, liquid C+P ingestion immediately after exercise increases fat oxidation, increases recovery, and improves subsequent same day, 60 min efforts relative to isoenergetic CHO ingestion.

Figure 1

Decrease in total distance traveled in a time trial (PM_ex) performed 6 h after an initial time trial (AM_ex). During the recovery period between AM_ex and PM_ex nutritional interventions included early post exercise carbohydrate + protein supplements (C+P) and a later solid meal and early carbohydrate supplement (CHO) and a later solid meal. *The performance decrement in C+P is significantly less than in CHO (p ≤ 0.05).

Figure 2

Decrease in power output during a time trial (PM_ex) performed 6 h after an initial time trial (AM_ex). During the recovery period between AM_ex and PM_ex nutritional interventions included early post exercise carbohydrate + protein supplements (C+P) and a later solid meal and early carbohydrate supplement (CHO) and a later solid meal. *The decrease in power output in C+P is significantly less than in CHO (p ≤ 0.05).

Figure 3

Serum glucose concentration during AM_ex and PM_ex. During the recovery period between AM_ex and PM_ex nutritional interventions included early post exercise carbohydrate + protein supplements (C+P) and a later solid meal and early carbohydrate supplement (CHO) and a later solid meal. Serum glucose concentration decreased from AM45 to PM15 (p ≤ 0.05) but there were no other differences over time or between conditions.

Figure 4

Serum lactate concentration during AM_ex and PM_ex. During the recovery period between AM_ex and PM_ex nutritional interventions included early post exercise carbohydrate + protein supplements (C+P) and a later solid meal and early carbohydrate supplement (CHO) and a later solid meal. Serum lactate concentration decreased at each time point from AM15 to PM15 (p ≤ 0.05) but there were no other differences over time or between conditions.

Figure 5

Carbohydrate and fat oxidation during AM_ex and PM_ex. During the recovery period between AM_ex and PM_ex nutritional interventions included early post exercise carbohydrate + protein supplements (C+P) and a later solid meal and early carbohydrate supplement (CHO) and a later solid meal. There was a time effect for carbohydrate oxidation but no group effects or group by time interactions. *While rates of fat oxidation were higher in C+P during both PM time points (vs. AM_ex); in CHO, rates of fat oxidation were lower during both PM time points relative to the AM time points (p ≤ 0.05).