Effects of 4:1 carbohydrate/protein solution versus a carbohydrate-alone solution on IL-6, TNF-α, and cortisol during prolonged cycling in hot environmental conditions

Shorter Duration Time Trial Performance and Recovery Is Not Improved by Inclusion of Protein in a Multiple Carbohydrate Supplement

Wolfe, AS, Brandt, SA, Krause, IA, Mavison, RW, Aponte, JA, and Ferguson-Stegall, LM. Shorter duration time trial performance and recovery is not improved by inclusion of protein in a multiple carbohydrate supplement. J Strength Cond Res 31(9): 2509-2518, 2017-Ingesting multiple carbohydrate (CHO) types during exercise can improve endurance performance compared with single CHO only. Adding protein to a multiple CHO beverage has been shown to increase cycling time to exhaustion (TTE) compared with a single CHO beverage. However, it is unclear if improvements were due to multiple CHO or protein, and TTE protocols are not representative of typical race events. This study investigated whether adding protein to a multiple CHO beverage improved performance and recovery in 2 same-day cycling time trials (TTs) compared with isocaloric multiple CHO only. Ten cyclists (37.4 ± 8.9 years; V[Combining Dot Above]O2max 54.6 ± 6.5 ml·kg·min) performed a familiarization and 2 randomized, crossover, double-blinded experimental trials consisting of pretrial leg strength testing, 40-km TT, 30-min recovery, 10-km TT, and posttrial leg strength testing. Seven 275 ml doses of multiple CHO (MCO) or multiple CHO+protein (MCP) were ingested during the protocol. Blood glucose, lactate, heart rate (HR), and rating of perceived exertion (RPE) were also measured. Continuous variables were analyzed with paired t-tests, and repeated measures with repeated-measures analysis of variance. No differences existed between MCO and MCP in 40-km TT time (81.6 ± 2.8 vs. 81.9 ± 2.9 minutes, respectively, p = 0.94), or in 10-km time (24.0 ± 0.9 vs. 23.9 ± 1.0 minutes, p = 0.97). Blood glucose was higher before 10-km TT in MCO compared with MCP (3.78 ± 0.20 vs. 3.31 ± 0.19 mmol·L, p = 0.002). No treatment differences were found for lactate, HR, RPE, or strength recovery. When using a protocol and performance measures that replicate realistic, shorter duration events, adding protein to a multiple CHO beverage does not improve performance compared with multiple CHO only.

The effect of milk on recovery from repeat-sprint cycling in female team-sport athletes

The consumption of milk following eccentric exercise attenuates the effects of muscle damage in team-sport athletes. However, participation in team sport involves both concentric-eccentric loading and metabolic stress. Therefore, the aim of this study was to investigate the effects of postexercise milk consumption on recovery from a cycling protocol designed to simulate the metabolic demands of team sport. Ten female team-sport athletes participated in a randomised crossover investigation. Upon completion of the protocol participants consumed 500 mL of milk (MILK) or 500 mL of an energy-matched carbohydrate (CHO) drink. Muscle function (peak torque, rate of force development, countermovement jump, 20-m sprint), muscle soreness and tiredness, serum creatine kinase, high-sensitivity C-reactive protein, and measures of oxidative stress (protein carbonyls and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio) were determined at pre-exercise and 24 h, 48 h, and 72 h postexercise. MILK had a possible beneficial effect in attenuating losses in peak torque (180°/s) from baseline to 24 h (3.2% ± 7.8% vs. -6.2% ± 7.5%, MILK vs. CHO) and a possible beneficial effect in minimising soreness (baseline-48 h; baseline-72 h) and tiredness (baseline-24 h; baseline-72 h). There was no change in oxidative stress following the exercise protocol, though a likely benefit of milk was observed for GSH/GSSG ratio at baseline-24 h (0.369 ×/÷ 1.89, 1.103 ×/÷ 3.96, MILK vs. CHO). MILK had an unclear effect on all other variables. Consumption of 500 mL of milk after repeat sprint cycling had little to no benefit in minimising losses in peak torque or minimising increases in soreness and tiredness and had no effect on serum markers of muscle damage and inflammation.

Effects of macro- and micronutrients on exercise-induced hepcidin response in highly trained endurance athletes

Iron deficiency has ergolytic effects on athletic performance. Exercise-induced inflammation impedes iron absorption in the digestive tract by upregulating the expression of the iron regulatory protein, hepcidin. Limited research indicates the potential of specific macro- and micronutrients on blunting exercise-induced hepcidin. Therefore, we investigated the effects of postexercise supplementation with protein and carbohydrate (CHO) and vitamins D3 and K2 on the postexercise hepcidin response. Ten highly trained male cyclists (age: 26.9 ± 6.4 years; maximal oxygen uptake: 67.4 ± 4.4 mL·kg–1·min–1 completed 4 cycling sessions in a randomized, placebo-controlled, single-blinded, triple-crossover study. Experimental days consisted of an 8-min warm-up at 50% power output at maximal oxygen uptake, followed by 8 × 3-min intervals at 85% power output at maximal oxygen uptake with 1.5 min at 60% power output at maximal oxygen uptake between each interval. Blood samples were collected pre- and postexercise, and at 3 h postexercise. Three different drinks consisting of CHO (75 g) and protein (25 g) with (VPRO) or without (PRO) vitamins D3 (5000 IU) and K2 (1000 μg), or a zero-calorie control drink (PLA) were consumed immediately after the postexercise blood sample. Results showed that the postexercise drinks had no significant (p ≥ 0.05) effect on any biomarker measured. There was a significant (p < 0.05) increase in hepcidin and interleukin-6 following intense cycling intervals in the participants. Hepcidin increased significantly (p < 0.05) from baseline (nmol·L–1: 9.94 ± 8.93, 14.18 ± 14.90, 10.44 ± 14.62) to 3 h postexercise (nmol·L–1: 22.27 ± 13.41, 25.44 ± 11.91, 22.57 ± 15.57) in VPRO, PRO, and PLA, respectively. Contrary to our hypothesis, the drink compositions used did not blunt the postexercise hepcidin response in highly trained athletes.