Nutritional supplementation not only helps in improving and maintaining performance in sports and exercise, but also contributes in reducing exercise fatigue and in recovery from exhaustion. Fish oil contains large amounts of omega-3 fatty acids, eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3). It is widely known that omega-3 fatty acids are effective for improving cardiac function, depression, cognitive function, and blood as well as lowering blood pressure. In the relationship between omega-3 fatty acids and exercise performance, previous studies have been predicted improved endurance performance, antioxidant and anti-inflammatory responses, and effectivity against delayed-onset muscle soreness. However, the optimal dose, duration, and timing remain unclear. This review focuses on the effects of omega-3 fatty acid on muscle damage and function as evaluated by human and animal studies and summarizes its effects on muscle and nerve damage, and muscle mass and strength.

This study aimed to investigate the effect of supplementation of fish oil rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the damage of the biceps brachii after eccentric contractions (ECCs) of the elbow flexors, particularly focusing on muscle stiffness. Sixteen men were included in this double-blind, placebo-controlled, parallel design study and the participants were randomly assigned to the EPA and DHA supplement group (EPA, n = 8) and placebo group (PL, n = 8). They consumed either EPA 600 mg and DHA 260 mg per day or placebo supplement for 8 weeks prior to exercise. Moreover, they performed six sets of 10 ECCs at 100% maximal voluntary contraction (MVC) using a dumbbell. Changes in MVC torque, range of motion (ROM), upper arm circumference, muscle soreness, muscle echo intensity, and muscle stiffness were assessed before exercise; immediately after exercise; and 1, 2, and 5 days after exercise. MVC torque and ROM were significantly higher in the EPA group than in the PL group after ECCs (p < 0.05). Muscle soreness, upper arm circumference, and muscle echo intensity were significantly higher in the PL group than in the EPA group after ECCs (p < 0.05). In addition, muscle stiffness at 150° was significantly higher in the PL group than in the EPA group immediately after ECCs (p < 0.05). The present study showed that EPA and DHA supplementation has a positive role in inhibiting muscle stiffness after ECCs. This trial (UMIN000028165) was registered on 10th/July/2017.

BACKGROUND: Eccentric contractions (ECC)-induced muscle damage and activation pattern are not fully understood. OBJECTIVE: To investigate the activation level and damage in each muscle and site after ECC. METHODS: Eleven men performed 30 isokinetic ECC of the elbow flexors. Maximal voluntary isometric contraction (MVC) torque, range of motion of the elbow joint (ROM), delayed onset muscle soreness(DOMS), transverse relaxation time (T2), and cross-sectional area (CSA) were measured immediately before, immediately after, and 1, 3, 5 days after ECC. RESULTS: MVC and ROM significantly decreased while DOMS significantly increased until 3 days after ECC. The CSA of the brachialis significantly increased after ECC. The T2 in biceps brachii and middle and distal brachialis increased significantly at post (p< 0.01) day 1 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01), and day 3 (middle; p< 0.01, distal; biceps brachii, p< 0.05, brachialis, p< 0.01). In addition, after 5 days only the distal brachialis has shown a significant increase(p< 0.01). CONCLUSIONS: Following maximal ECC the activation pattern and muscle damage differ among the elbow flexors depending upon the individual muscle and site of recording.

The purpose of this study was to examine the effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on muscle strength and damage following a single bout of eccentric exercise. Eighteen untrained male subjects were assigned to HMB and Whey protein (HMB + Whey; 3 g/day HMB and 36.6 g/day whey protein, n = 6), HMB (3 g/day, n = 6), or whey protein (36.6 g/day, n = 6) groups. Ingestion commenced 7 days before non-dominant elbow flexor eccentric exercise (30 deg/sec, 6 reps × 7 sets) and continued until 4 days post-exercise. The maximal isometric strength, muscle soreness, plasma creatine kinase (CK), lactate dehydrogenase (LDH) were assessed pre-exercise, and at 1, 2, 3, and 5 days after exercise. The change scores of maximal isometric strength significantly decreased at day 1, 2, and 5 in the whey protein group compared to pre value and that in HMB + Whey protein and HMB groups decreased at day 1 and 5. The muscle soreness significantly increased in the whey and HMB + Whey protein groups at day 3 compared to pre value (p < 0.05). CK and LDH significantly increased (time effect: p < 0.05) after exercise. However, all data were not significant difference among the groups. These results suggest that ingestion of combined HMB and whey protein does not have a role to inhibit muscle strength loss and soreness, and decrease in muscle damage markers after eccentric exercise in comparison with HMB and whey protein alone.

Background: Although the ingestion of total omega–3 fatty acids (omega–3) is positively related with muscular strength in older persons, little is known about the effect of omega–3 plasma levels on muscular function before and after exercise in young men. Moreover, omega–3 supplementation has a positive role in exercise-induced acute muscle damage. This study investigated the relationship between plasma omega–3 in the blood and promotion and preservation of muscle strength after eccentric contractions (ECCs) in young men. Methods: Thirty-two healthy young men participated in this study. We assessed plasma omega–3 level and the maximal voluntary contraction (MVC). Twenty-six out of them exercised 60 ECCs at 100% MVC. We measured the MVC torque, flexibility before and immediately after exercise, 1–5 days post exercise. Results: The levels of eicosapentaenoic acid (EPA) and EPA/arachidonic acid were positively associated with muscle strength (p < 0.05). Higher levels of omega–3 EPA and docosahexaenoic acid prevented the reduction in the MVC and limited joint flexibility after ECCs. Conclusions: The present study reveals that higher levels of EPA are important to promote muscle strength and preserve the strength loss after exercise.

Purpose: The effects of intake of STGs containing esterified eicosapentaenoic acid (EPA) and medium-chain triglycerides (MCTs) on cardiorespiratory endurance have not yet been reported. This study aimed to examine the efficacy of interesterified structured lipids EPA and MCTs on cardiorespiratory endurance. Methods: This 8-week randomized double-blind placebo-controlled parallel-group study involved 19 healthy men. The participants were randomly assigned to a group that received interesterified structured lipids EPA and MCTs (STG group, 9 participants) or a group receiving a PM of EPA and MCTs (PM group, 10 participants). The outcome measures were time to exhaustion (TTE) and time to reach the anaerobic threshold in the peak oxygen uptake (VO₂peak) test, VO₂peak, and anaerobic threshold. Results: The increase in TTE in the VO₂peak test after the intervention period compared with before the intervention period was significantly greater in the STG group (53 ± 53 s) than in the PM group (−10 ± 63 s; p < 0.05). Similarly, the increase in time to reach the anaerobic threshold was significantly greater in the STG group (82 ± 55 s) than in the PM group (−26 ± 52 s; p < 0.001). Conclusion: This study demonstrated that the consumption of interesterified structured lipids EPA and MCTs improved endurance in humans.