A leucine-rich diet and exercise affect the biomechanical characteristics of the digital flexor tendon in rats after nutritional recovery

Abstract

An increase in the capacity of athletic performance depends on adequate nutrition, which ensures optimal function of the musculoskeletal system, including tendon stability. However, little is known about the status of tendons and extracellular matrix modifications during malnutrition and nutritional recovery when leucine is used in response to exercise conditioning. The purpose of this study was to evaluate the collagen content and biomechanical aspects of the deep digital flexor tendon (DDFT) in malnourished rats submitted to nutritional recovery (control diet or leucine-rich diet) and aerobic physical activity. After 60 days of undernourishment (6% protein diet), the malnourished rats were subsequently nutritionally recovered with a control diet or leucine-rich diet and trained or not (swimming, without overload) for 5 weeks. The biomechanical analysis and quantification of hydroxyproline were assessed in the DDFT in all experimental groups. The leucine-rich diet increased hydroxyproline content in the tension region, independently of the training. In the compression region, hydroxyproline content was higher in the malnourished and leucine-trained groups. Biomechanical analysis showed a lower load in the malnourished and all-trained groups. The lowest stress was observed with control-trained animals. The nutritional-recovered groups showed higher strain values corresponding to control group, while the lowest values were observed in malnourished and trained groups. The results suggest that a leucine-rich diet stimulates collagen synthesis of the DDFT, especially when in combination with physical exercise, and seems to determine the increase of resistance and the biomechanical characteristics of tendons.

Whey protein hydrolysate augments tendon and muscle hypertrophy independent of resistance exercise contraction mode

“…However, to our knowledge, no previous studies on humans have investigated the combination of resistance training and high‐leucine whey protein hydrolysate ingestion on tendon collagen synthesis. In this regard, it is interesting that recent observations on rodents indicate that the amino acid, leucine, could be of specific importance for stimulating collagen synthesis (Barbosa et al., ). Furthermore, the type of feeding, bolus (Dideriksen et al., ) vs repeated small dosages (Holm et al., ) may affect collagen synthesis differently, with a bolus‐type feeding required for maximal stimulation of collagen synthesis (Dideriksen et al., ).…”

“…Collectively, these findings suggest that loading intensity and/or contraction mode comprise driving factors for tendon hypertrophy. Moreover, the effect of protein supplementation combined with resistance training on tendon hypertrophy has not previously been investigated, although a recent study indicates a potentially important role for the amino acid leucine in collagen synthesis in rodents (Barbosa et al., ).…”

Effects of Long-Term Physical Activity and Diet on Skin Glycation and Achilles Tendon Structure

“…However, the present study made no attempt to determine micro-nutritional diet composition. At a macro-nutritional level, a study in humans reported that leucine-rich protein supplementation during an exercise intervention resulted in greater hypertrophy of both tendon and muscle [57], which is supported by a study on nutritional recovery in rats, which reported increased tendon collagen synthesis with a leucine-rich diet [58]. These results suggest that a protein-rich diet could result in tendon hypertrophy, perhaps especially during youth when the tendon is formed.…”

Minimizing Injury and Maximizing Return to Play: Lessons from Engineered Ligaments

“…However, whether this was the result of a direct effect on the tendon or an indirect effect related to greater muscle hypertrophy and strength gains is still unclear. In support of a role for whey, a similar tendon hypertrophy was seen in rats following 5 weeks of leucine supplementation after a period of malnutrition [43]. The molecular target of whey and leucine is mTORC1 [44], and as described in Sect.…”