Hydrolysed Collagen Supplementation Enhances Patellar Tendon Adaptations to 12 Weeks' Resistance Training in Middle-Aged Men

Abstract

Resistance exercise (RE) with hydrolysed collagen (HC) supplementation increases collagen synthesis in young and middle-aged populations, and further enhances tendon adaptations to chronic RE in young athletes. However, it is unknown if middle-aged tendon can benefit from chronic RE with HC supplementation. We investigated the effects of 12-weeks' RE, combined with HC supplementation, on changes in patellar tendon (PT) properties in middle-aged men. In a double-blind design, 20 recreationally active men (age, 47 ± 5 years) were randomly assigned to a placebo (PLA, n = 11) or collagen (COL, n = 9) group. Both cohorts completed progressive lower-limb RE twice weekly for 12 weeks and were supplemented post-RE with COL (30 g HC and 50 mg vitamin C) or PLA (30.5 g maltodextrin and 50 mg vitamin C). The following were assessed before and after the 12-week intervention: barbell back squat 10-repetition maximum (10-RM); vastus lateralis (VL) muscle thickness and PT cross-sectional area (CSA at 25%, 50% and 75% tendon length) using ultrasonography; isometric knee extension maximum voluntary torque (MVT) and peak rate of torque development (pRTD), PT stiffness (k) and Young's modulus (ℰ) using ultrasonography and isokinetic dynamometry. MVT_, pRTD, 10-RM and VL thickness all increased post-training (p < 0.05), but there were no group × time interactions (p > 0.05). Mean PT CSA increased more in COL (+6.8 ± 5.4 mm²) than PLA (+1.2 ± 2.1 mm², group × time p = 0.027). Similarly, k and ℰ increased more in COL (k, +661 ± 331 N/mm and ℰ, +0.21 ± 0.13 GPa) than PLA (k, +247 ± 305 N/mm, group × time, p = 0.009 and ℰ, +0.09 ± 0.13 GPa, group × time, p = 0.018). In conclusion, 12-weeks' RE with 30 g HC supplementation augmented gains in PT CSA, stiffness and Young's modulus in middle-aged men.

Keywords: connective tissue; strength training; tendon stiffness; vitamin C.

FIGURE 1

CONSORT flow diagram showing participant recruitment and intervention timeline. PLA = placebo group and COL = collagen group.

FIGURE 2

(A) Representative ultrasound image of patellar tendon (PT) cross sectional area at 25%, 50% and 75% PT length; (B) example of the force‐elongation curve during a 6 s ramped isometric maximum voluntary contraction (MVC) and (C) ultrasound image depicting changes in PT length from rest to MVC (solid arrow represents resting tendon length and dashed arrow represents tendon length at MVC). For this image, two separate ultrasound video frames from the proximal and distal ends of the tendon (taken during two separate MVCs) were joined together at a common echo‐absorbent reference point at 50% PT length. N.B. This image is for illustration purposes only. The method used to determine PT elongation is detailed in Section 2.6.3.

FIGURE 3

Absolute explosive torque before (dashed line) and after (solid line) 12 weeks’ resistance training without (A, PLA, n = 10) and with 30 g hydrolysed collagen supplementation (B, COL, n = 9) and explosive torque normalised to maximum voluntary torque (MVT) before (dashed line) and after (solid line) 12 weeks’ resistance training without (C, PLA, n = 10) and with 30 g hydrolysed collagen supplementation (D, COL, n = 9).

FIGURE 4

Absolute rate of torque development (RTD) before (dashed line) and after (solid line) 12 weeks’ resistance training with (A, COL = 9) without 30 g hydrolysed collagen supplementation (B, PLA, n = 10) and normalised RTD before (dashed line) and after (solid line) 12 weeks’ resistance training with (C, COL, n = 9) and without 30 g hydrolysed collagen supplementation (D, PLA, n = 10).

FIGURE 5

Patellar tendon cross sectional area (mm²) before (open circles) and after (black circles) 12 weeks’ resistance training in A. PLA (n = 11) and B. COL (n = 9). *Greater than pre (p < 0.05).

FIGURE 6

(A) Patellar tendon stiffness (N/mm) and (B) Young’s modulus (GPa) before (circles) and after (triangles) 12 weeks’ resistance training in COL (n = 9) and PLA (n = 11). *Greater than pre, # group × time interaction (p < 0.05).