Effects of protein and carbohydrate on resistance training
This fitness blog examines how pre- and post-exercise protein/carbohydrate intake can enhance resistance training and why a personal trainer might want to recommend this approach to clients.
The role of protein
In a previous blog, we looked at the role of protein and recommended intake. However, new research reported in the ACSM’s Health & Fitness Journal (Vol 17/No 2) has found that anyone looking to enhance resistance training should consider not only the amount of protein they consume but also the time of day they consume it – in particular the importance of consuming protein pre- and post-exercise.
The best time to ingest protein and carbohydrate
The ACSM article, entitled “Enhancing Resistance Training Results With Protein/Carbohydrate Supplementation” by Wayne L Westcott and Rita La Rosa Loud, states that:
“Based on numerous study findings, it would seem that the best time to ingest extra protein is just before or just after a strength training session because doing so significantly enhances muscle development.”
Personal trainers can pass this advice on to clients following resistance training programmes.
An example is a 2006 study conducted by Paul Cribb and Alan Hayes from Victoria University in Australia prescribed a strength training programme, four days a week for 10 weeks, for a group of 17 men with a mean age of 22.
Each individual was given an additional supplement comprising 40g of protein, 43g of carbohydrate and 7g of creatine monohydrate. Those who took the supplement directly before and after training achieved greater benefits in terms of increased muscle mass and decreased body fat than those who ingested it in the morning and evening.
Further exercise and nutrition studies
A further study by WL Westcott, J Varghese, N DiNubile et al in 2011, also quoted in the ACSM article, tested the hypothesis over a 36-week period with three study groups comprising 52 previously untrained women and men, aged between 39 and 82.
One group performed a set routine of strength training exercises without supplements; another group both followed the exercise routine and consumed a protein and carbohydrate shake immediately after training; and a control group neither exercised nor took the supplement.
The findings were that only the group that trained and consumed the post-exercise supplement benefited from a significant increase in lean weight.
The role of creatine
In the first of the two studies mentioned above, the supplement included creatine monohydrate as well as protein and carbohydrate. As any good personal trainer will be aware, creatine can be associated with water gain, which can affect how much a person weighs and can therefore alter any calculation of their muscle mass.
However, the second study was conducted without the use of creatine and with smaller amounts of protein and carbohydrate in the supplement than was given in the first study, and yet it still produced positive results to back up the theory.
Protein and carbs or protein alone?
Studies have shown that protein taken on its own will help to increase muscle fibres, but also that carbohydrate can also have a role to play, in particular to replenish the glycogen an individual will lose, for example, during an intensive workout with a personal trainer. For those training on a regular basis, carbohydrate intake after training can also aid recovery, allowing them to train harder at the next session.
Protein drinks and shakes
Many fitness instructors will work with clients who consume protein drinks and shakes to enhance resistance training.
The studies detailed above, along with other studies mentioned in the ACMS article, suggest that personal trainers should recommend that these drinks and shakes be taken immediately before and after resistance training programmes for maximum benefit.
These may be shop-bought powders or made from scratch using natural ingredients (see our blog on post-exercise protein shakes for comparisons and suggestions for homemade shakes).
Whole milk or fat free?
The article also quotes studies that suggest that:
“…milk-based proteins promote muscle protein accretion better than soy-based proteins when ingested after resistance exercise”.
It also says that whole milk is more effective than an equal quantity of fat-free milk; however if fat-free milk is consumed to an equal calorific value of a volume of whole milk, the benefits will be the same.
In conclusion, although resistance training has been shown to benefit people of all ages and levels of fitness by increasing muscle mass and bone density and reducing body fat, a personal trainer can help clients get further benefits by recommending the correct nutritional intake before and after training.
The recommended guidelines are as follows:
Bodyweight 50kg = 18-22 g protein and 28-32g carbohydrate
Bodyweight 70kg = 26-30 g protein and 40-44 carbohydrate
Bodyweight 80kg = 30-34 g protein and 46-50g carbohydrate
Bodyweight 100kg = 38-42 g protein and 58-62g carbohydrate
However, as always, it’s important for a fitness instructor to encourage all their clients to follow a healthy balanced diet and to consult a doctor before making any major changes to their eating habits.