Carbohydrate and Protein Supplement on Neuromuscular Recovery After Prolonged Endurance Training

Carbohydrate and protein supplement on Neuromuscular Recovery after Prolonged Endurance Training

Introduction

Prolonged endurance training leads to glycogen depletion and muscle catabolism. Nutrition ingestion during both exercise and recovery could improve muscle damage, recovery of neuromuscular function, muscle soreness, endurance capacity and physical performance. It is well established that the consumption of carbohydrate could improve endurance performance, delay the time to fatigue and increase power output during the later stages of prolonged exercise and additionally, the consumption of carbohydrate beverage after prolonged endurance exercise also help the recovery from muscle glycogen depletion.

On the other side, currently, protein supplements have become a popular dietary supplement used by athletes, recreationally active adults and soldiers. From both the consumers and researchers, proteins might have effects in increasing muscle mass, improving exercise recovery and performance. Marketing claims have convinced many consumers that protein supplements, whether consumed alone or in combination with carbohydrate, will enhance physical performance by attenuating carbohydrate oxidation during prolonged steady-state exercise and will hasten muscle glycogen repletion during recovery. Moreover, the consumption of protein supplement might enhance rates of protein synthesis and decrease rates of protein degradation, and optimize recovery of muscle function and physical performance following exercise by attenuating muscle damage and muscle soreness. Even though those discoveries are valid, it is difficult to determine whether these benefits are influenced by the timing of beverage ingestion (before, during, or after exercise), by the way in which recovery is measured, or by the time given between the exercise and the assessment of recovery.

To exam the hypothesis that protein supplements enhance recovery of muscle function and physical performance by attenuating muscle damage and soreness after prolonged endurance training, this literature review looked over some articles within the last 10 years, which made comparison of carbohydrate alone and carbohydrate plus protein supplement under different situations and will discuss the specific research in details, distinguish the difference and find the consistency and mechanism in those studies.

Nonisocalric study

A study done by Breen, Tipton and Jeukendrup in 2009 was focused on whether adding protein to a CHO beverage would improve late-exercise cycle time-trial performance over CHO alone. The CHO beverage dose was 65g/h, which had met the recommended upper limit to attain peak exogenous CHO oxidation rates. The treatment group was given 19g/h PRO aside from the 65g/h CHO. The 12 trained male cyclists performed 120 min of steady state cycling at 55% of maximal oxygen intake and were given the beverage every 15 minutes. Each individual serves as his own control. A maximum isometric strength test was given 24h after recovery to test sports performance and muscle recovery. The conclusion was that the addition of protein did not improve late-exercise cycle time-trial performance or indices of recovery at 24h postexercise. The study also made comparison with other similar studies that showed positive effect of additional protein. The researchers pointed out that the CHO intake in those studies were too low (<50g/h) to attain peak exogenous oxidation rate and protein plus CHO provided more energy than CHO alone.  Thus, the benefit of adding protein to CHO likely was due to the additional energy delivered by protein as opposed to a protein per se.