Effects of exercise on the diameter of collagen fibrils in the central core and periphery of the superficial digital flexor tendon in foals.

The research study investigated the impact of exercise on the diameter of collagen fibrils, which are a structural component of the superficial digital flexor tendon (SDFT) in foals. The study concluded that physical activity to a certain extent encourages collagen fibril restructuring in foals’ SDFT. Lack of exercise may result in delayed fibril development, although this postponement can be partly made up by incorporating more rigorous physical activities at a latter age.

Methodology

• The study consisted of 43 Dutch Warmblood foals categorized as group 1, 2, and 3.
• All foals within group 1 were not exercised and kept in stalls from 1 week until 5 months of age. Foals in group 2 were kept in stalls in the same period but were subjected to exercise. Group 3 foals were left to pasture.
• SDFT biopsy samples were collected at two, five, and eleven months. After the age of five months, eight foals from each group were euthanized for sample collection. The remaining foals were kept together until euthanized at 11 months for the collection of final samples.

Results

• Using electron microscopy, all specimens were analyzed for Collagen Fibrillar Index (CFI), Mass Average Diameter (MAvD), and Area Dependent Diameter (ADD).
• At the two-month mark, the study found no significant exercise-related differences in fibril distribution among the groups.
• However, at 5 months, ADD was significantly greater in peripheral specimens in group 1 (non-exercised foals) compared to group 3 (pastured foals).
• By 11 months, there was less MAvD in the core samples of group 3 compared to the other groups, indicating less fibrillar diameter. However, MAvD was significantly less in the peripheral samples from groups 2 and 3.

Conclusions

• The data suggests that exercise plays a crucial role in the restructuring of collagen fibrils in foals’ SDFT, indicating it being an exercise-driven process.
• This suggests that a lack of exercise may delay fiber development in foals. Increased exercise, introduced at a later age, can partially overcome this delay.
• The type of exercise may also influence the remodeling of the foals’ SDFT. The study implies that pasture rearing, or free-style exercise, seems to support the natural fibril development more than no exercise or structured exercise in confinement.