Protein supplements are very popular in athletic populations. This is justified by the fact that a large number of studies have demonstrated that protein intake post exercise, and whey protein in particular, stimulates muscle protein synthesis. By analogy, research also has clearly demonstrated that protein ingestion before bedrest, especially casein, suppresses overnight muscle protein degradation, which in turn also facilitates long-term training adaptation. In the above context we refer to the muscle proteins involved in muscle contraction, the so-called myofibrillar proteins. However, besides the muscle fibers per se, also connective tissue plays a pivotal role in muscle force and power production. Interestingly, some research data suggest that oral collagen peptide (CP) supplementation might promote connective tissue synthesis during training.
But, how strong is the evidence in this regard?
The pivotal role of collagen in muscle
Skeletal muscle tissue is largely composed of muscle fibers. However, for muscles to be able to generate high force and power outputs, the individual muscle fibers must act as a ‘team’. Therefore, the fibers are embedded in a tight network of connective tissue, the so-called ‘extracellular matrix’, which is largely composed of collagen. This network links the ‘soldiers’ (~muscle fibers) to form a functional ‘army’ (~muscle). Furthermore, also tendons, ligaments and cartilage are largely composed of collagen. Clearly, collagen plays a pivotal role in muscle force production. Strong muscles require strong and healthy connective tissue.
What makes the difference between whey protein, collagen protein, and gelatin?
High-quality whey protein isolate supplements are first choice to stimulate myofibrillar protein synthesis because of high fraction of essential amino acids. In this regard, the high leucine content in whey protein plays a key role in the activation of myofibrillar protein synthesis. Conversely, CP contains lower fraction of essential amino acids such as leucine. However, the non-essential amino acids glycine, proline, and hydroxyproline are more abundant. Glycine, proline, and hydroxyproline are primary substrates for the production of collagen. CP, and gelatin which is extracted from bones and skins of beefs, pigs, and fish. The amino acid profile of CP and gelatin is similar. However, the amino chains of CP have been cut into smaller pieces which, in contrast to gelatin, makes them easily soluble in water.
Does collagen peptide supplementation stimulate muscle collagen synthesis?
In fact only one study to date has investigated the effect of CP supplementation in the form of gelatin on collagen synthesis in humans. Shaw and co-workers (2017) administered a placebo, or either 5 or 15g gelatin, 1 hour before a short high-intensity exercise bout in young healthy volunteers. Compared with a placebo, 15 but not 5g gelatin increased blood PINP, a blood marker of whole body collagen synthesis. However, this probably largely reflects elevated bone collagen turnover. Furthermore, blood serum extracted 1 hour after 15g gelatin ingestion, stimulated collagen synthesis rate in an in vitro engineered ligament preparation. However, such experimental approach does not account for potential effects of exercise per se on muscle collagen synthesis. More research is needed to prove that oral CP supplementation can enhance muscle collagen synthesis post exercise in healthy humans.
Collagen supplementation suppresses exercise-induced musculoskeletal pain.
The incidence of soft tissue (muscle, tendons, ligaments, joint cartilage) injuries in both recreational and elite sports is high. Injuries may result from either an acute event or from long-term overload. In addition, many athletes, even in the absence of explicit injury or disease, experience pain during and/or after exercise. In this regard it is important to note that pain per se can impair exercise performance. Research findings consistently showed that both CP and gelatin supplementation can reduce exercise-induced musculoskeletal pain. Twelve to 24 weeks of CP intake at a rate of 5-10g per day reduced activity-related joint pain (Clark et al, 2008; Zdzieblik et al, 2017). In another study 20g of daily CP for 7 days before and 2 weeks after exercise-induced muscle damage alleviated muscle soreness (Clifford et al, 2019). CP administration (2.5g twice daily, 6 months) also reduced pain in patients with Achilles tendinopathy enrolled in a rehabilitation program (Praet et al, 2019). Finally, post exercise CP intake (5g) for 6 months improved the subjective perception of ankle stability in athletes with a history of ankle sprain. Taken together the above findings indicate that CP supplementation can suppress exercise-related joint or tendon pain in athletic populations.
Does collagen peptide intake stimulate recovery?
It is well-established that whey protein intake stimulates post exercise myofibrillar protein repair. It is therefore reasonable to postulate that a similar effect may occur in muscle connective tissue due to CP supplementation. In this regard, compared with the absence of any protein intake, CP after exercise was found to stimulate some indirect markers of muscle protein synthesis (Oertzen-Hagemann et al, 2019). However, whether such effect also occurs when CP is co-ingested with a recommended dose of post exercise whey protein (20-40g) intake, remains to be established.
Which dose of collagen peptide should be ingested and when?
Research with regard to the effects of CP supplementation in exercise and training is in its infancy. Available studies have used very different dosages ranging from 2.5 to 20g per day, different timings (before or after exercise) and different durations (days to months) of CP ingestion. Based on available findings it is currently impossible to define well-validated guidelines for CP supplementation in the context of exercise, training, or rehabilitation. More clinical trials are needed in order to better understand the effects of CP in healthy and injured athletic populations.
Take home message
- Collagen is important for muscle force and power production
- Collagen peptide supplements deliver high fraction of the amino acids glycine, proline, and hydroxyproline, which are pivotal in collagen synthesis.
- Collagen peptide ingestion before or after exercise may alleviate exercise-induced muscle, joint, or tendon pain.
- Whether collagen peptide supplementation may facilitate muscle repair following exercise remains to be established.
- Clark et al., 2008 ( https://doi.org/10.1185/030079908X291967 )
- Clifford et al., 2019 ( https://link.springer.com/article/10.1007%2Fs00726-019-02706-5 )
- Dressler et al., 2018 ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5950747/ )
- Oertzen-Hageman et al., 2019 ( https://doi.org/10.3390/nu11051072 )
- Praet et al., 2019 ( https://doi.org/10.3390/nu11010076 )
- Shaw et al., 2017 ( https://doi.org/10.3945/ajcn.116.138594 )
- Smith et al., 2021 ( https://doi.org/10.1152/japplphysiol.00139.2020 )
- Zdzieblik et al., 2017 ( https://doi.org/10.1139/apnm-2016-0390 )