Background/Aims: This study aimed to investigate the effect of low dose fish oil diets on skeletal muscle contraction and low frequency fatigue after initial fatiguing stimulation.
Methods: 18 male Wistar rats were fed (for 5w) a 10% fat diet containing: olive oil (OO); or 0.31% (lowFO); or 1.25% moderate (modFO) NuMega, High-DHA tuna fish oil in OO. The constant-flow autologous blood-perfused hindlimb was prepared in vivo and stimulated via sciatic nerve. Tetanic stimulations preceded low frequency stimulation protocols at 2Hz continuous and 5Hz burst.
Results: FO diets increased muscle DHA (gastrocnemius: OO 7.8 ± 0.7; LowFO 20.0 ± 0.1% total phospholipid fatty acids) No difference was found in tetanic force (~200 N.100g-1), but rate of tetanic force development was faster in LowFO and ModFO (24.6 ± 3.9; 21.1 ± 3.4 vs 16.3 ± 1.0 kN.s-1; p<0.05) After the tetanic contraction, twitch force development was greater in FO rats throughout 2Hz stim. The 5Hz burst contractions were of greater force in FO rats (peak force: OO 30.0 ± 4.3; LowFO 50.7 ± 7.4; ModFO 75.7 ± 11.4 N.100g-1; p<0.05) representing 14%; 25%; 35% of unfatigued peak responses; fatiguing finally to 6%; 17%; 15% .
Conclusions: Feeding rats diets supplemented with FO within a human dietary range increased muscle DHA and moderated low frequency fatigue. Low frequency fatigue leads to a greater sense of effort in walking and stair climbing and this effect of FO on fatigue that is commonly associated with daily activities of living warrants further investigation in human studies.
Funding source(s): N/A