Although older adults participate relatively less in strenuous physical activities, they are prone to mechanical muscle injuries during their routine exercise and mobility programs or normal daily activities. Muscle contusions, colloquially known as “bruised muscles”, are the most common injuries that accompany collisions and falls in older adults. Characterized by pain and swelling that accompany blunt force trauma to muscle fibers and connective tissue, the condition has historically received little geriatric attention due to the latter’s focus on fall-related fractures. Unfortunately, even in the absence of fractures, falls and similar impacts can cause muscle contusions that can leave older adults with weeks or even months of pain and debilitation. Recent research has clarified the duration of muscle healing (a few to several weeks) in younger adults.
Despite the lack of similar evidence in older adults, the effects of aging mechanisms in other organ systems along with previous rat model system experiments by the current research team suggest that healing durations are prolonged in older cohorts. Conventional treatment of contusions involves the use of NSAIDs, primarily for their pain-suppressing properties. Unfortunately, the muscle healing effects of NSAIDs have never been clinically validated, with some experts suggesting that the interventions may have counterproductive effects. Dietary supplements such as fish oils (FIOs) have shown considerable promise in reversing age-associated effects, with notable benefits related to their anti-inflammatory and antioxidant properties. While their utility in muscle repair remains untested, previous studies have suggested their potential to improve musculoskeletal health.
In a recent study published in the journal Nutrients, researchers conducted in vitro (mouse C2C12 myoblast cells) and in vivo (using aged (22 months) and adult (8 months) Sprague Dawley rats) experiments to investigate the potential benefits of fish oil supplements in muscle healing. Results revealed that aging significantly prolonged recovery periods in the rat model systems, with older rats demonstrating significantly slower recovery than their younger counterparts. Specifically, fish oil supplementation (containing 45% eicosapentaenoic acid or EPA) and 10% docosahexaenoic acid (or DHA) incorporated into the diet at a concentration of 33 g/kg) was shown to help attenuate the repair-delaying impacts of aging, with 78% of the fish oil-supplemented older rats demonstrating muscle healing rates comparable to their younger counterparts.
In adult rats, a 20-25% reduction in muscle contractility occurred 7 days after injury, while aged control rats showed a 30-40% reduction. Results from in vitro experiments on murine cell lines confirmed these findings and suggested that fish oil may enhance membrane resealing and repair, thereby contributing to accelerated healing. The present study highlights the muscle healing potential of fish oil supplements, which have been observed to accelerate muscle recovery in both aged rat models in vivo and in C2C12 cells in vitro. The data suggest that fish oil may promote recovery from mechanical injuries by enhancing membrane repair processes, involving key proteins such as dysferlin and TRIM72/MG53. The molecular mechanisms have not been investigated in detail, but the anti-inflammatory action of FIO omega-3 acids cannot be excluded.
Muscle cells are exposed to regular mechanical injury during contraction and therefore require a rapid and robust process to maintain the integrity of the sarcolemmal membrane and maintain cellular homeostasis. Key proteins involved in this repair process include dysferlin and TRIM72/MG53, the inhibition of which can increase muscle degeneration and, in turn, fibrosis, thus compromising or slowing recovery. Similarly, proteins for the integrity of the sarcolemmal reticulum, such as Grp78, are involved. The results of the study further confirmed the age-associated declines in the speed of muscle recovery in rats, but encouragingly observed the protective effects of FIO supplements in attenuating these declines. These results are not the only ones published by the group: the team has been working on the problem since 2015, when they had already found alterations in sphingolipid metabolism and in the process of cellular autophagy.
- Edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Scientific references
Russ DW, Sehested C et al. Nutrients 2024; 16:3511.
Russ DW et al. Lipids Health Dis. 2020, 19, 165.
Russ DW et al. Exp Gerontol. 2018; 111:241–252.
Iolascon G et al. J. Nutr. Health Aging 2017; 21:527.
Russ DW et al. Biogerontology 2015; 16:747–759.