Collagen peptides for tendon remodeling during a lower body resistance training program Original paper

In this randomized controlled trial, supplementation with collagen peptide did not enhance tendon remodeling induced by resistance training in men without injuries.

The effect of collagen peptides on tendon remodeling (a process in which tendons grow stronger) in response to exercise.

39 recreationally active men (ages 18–40) who hadn’t performed resistance training in the last 18 months.

The participants did not have any regular systematic physical training and had no prior lower-body injuries.

In this 15-week randomized controlled trial, the participants were divided into 2 groups who took either 15 grams of collagen peptides or a placebo once per day in combination with a resistance training program. The collagen or placebo treatments were taken immediately after exercise on resistance training days.

For 15 weeks, both groups performed resistance training sessions 3 times per week that primarily targeted the quadriceps and secondarily targeted the hamstrings and gluteus maximus. The sessions consisted of performing 3 exercises, 2–4 sets per exercise, using a resistance at which the participants could perform 6–12 repetitions.

Before and after the 15-week trial, the researchers collected measurements of patellar tendon size and mechanical properties on the participants’ dominant leg while they performed several knee extension and flexion movements. Maximum voluntary torque and force values, tendon stiffness, and tendon elongation were measured using torque measurements, electromyography, and ultrasound. MRI scans were also used to evaluate tendon dimensions (quadricep tendinous attachment area, mean and regional patellar tendon cross-sectional area, and patellar tendon moment arm).

The participants completed 3-day diet diaries of their food and fluid intake at weeks 3 and 13 to assess habitual energy and macronutrient intake.

Although there were general improvements to tendon properties in both groups after resistance training compared to before resistance training, there were no differences between the collagen and placebo groups for tendon-based outcomes.

Protein intake was higher in the collagen group.

The participants had a familiarization session with the maximal contractions of knee flexion and extension before their first main measurement session so that they could become acclimated to the tests. Without this first session, the posttraining results might have been artificially elevated simply due to the practice effect (i.e., the participants having more practice at performing the specific exercises). Additionally, each main measurement session was repeated after 3–5 days, so as to average the findings. These aspects of the study methodology increase the strength of the findings.