Muscle-specific glucose and free fatty acid uptake after sprint interval and moderate-intensity training in healthy middle-aged men

Abstract

We tested the hypothesis that sprint interval training (SIT) causes larger improvements in glucose and free fatty acid uptake (FFAU) in lower and upper body muscles than moderate-intensity training (MIT). Twenty-eight healthy, untrained, middle-aged men were randomized into SIT (n = 14, 4-6 × 30 s of all-out cycling/4 min recovery) and MIT groups [n = 14, 40-60 min cycling at 60% of peak O2 uptake (V̇o2 peak)] and completed six training sessions within 2 wk. Pre- and postmeasurements included V̇o2 peak, whole body (M-value), muscle-specific insulin-stimulated glucose uptake (GU), and fasting FFAU measured with positron emission tomography in thigh [quadriceps femoris (QF) and hamstrings] and upper body (deltoids, biceps, and triceps brachii) muscles. V̇o2 peak and M-value improved significantly by 6 and 12% in SIT, and 3 and 8% in MIT, respectively,. GU increased significantly only in the QF, and there was no statistically significant difference between the training modes. GU increased in all four heads of QF in response to SIT, but only in the vasti muscles in response to MIT, whereas in rectus femoris the response was completely lacking. Training response in FFAU in QF was smaller and nonsignificant, but it also differed between the training modes in the rectus femoris. In conclusion, SIT and MIT increased insulin-stimulated GU only in the main working muscle QF and not in the upper body muscles. In addition, the biarticular rectus femoris did not respond to moderate-intensity training, reflecting most probably poor activation of it during moderate-intensity cycling.

Right ventricular metabolic adaptations to high-intensity interval and moderate-intensity continuous training in healthy middle-aged men

“…A candidate was accepted to the study if the following criteria were fulfilled: male sex, age 40 -55 yr, body mass index 18.5-30 kg/m 2 , nonsmoking, and no exercise on regular basis [twice a week or less, peak oxygen uptake (V O2 peak) Յ 40 ml·kg Ϫ1 ·min Ϫ1 ]. A candidate was excluded if he had a condition that could potentially endanger the subject's health during the study or interfere with the interpretation of the results (7,17,18). Finally, 28 participants fulfilled the criteria.…”

“…The training interventions consisted of six exercise sessions within 2 wk (7,18). Each session was performed in supervised laboratory conditions.…”

“…Body composition was measured by bioimpedance monitor (InBody 720, Mega Electronics, Kuopio, Finland) (7,17). Whole body insulin-stimulated glucose uptake rate (M-value) was measured during euclycemic hyperinsulinemic clamp, as described in detail previously (7,17).…”

“…Whole body insulin-stimulated glucose uptake rate (M-value) was measured during euclycemic hyperinsulinemic clamp, as described in detail previously (7,17). V O2 peak was determined by a maximal exercise test on a cycle ergometer (Ergoline 800s; VIASYS Healthcare).…”

“…Many studies have shown that the health-enhancing benefits traditionally associated with high-volume endurance training can be achieved by considerably smaller volumes of HIIT (12,33,43). For instance, only six sessions of HIIT within 2 wk have been shown to increase exercise capacity and induce similar metabolic adaptations in skeletal muscles as six sessions of MICT (7,11). On the other hand, a recent metaanalysis showed that HIIT is not only tolerated but even seems to be superior to MICT in improving cardiovascular fitness in patients with lifestyle-induced cardiometabolic disease (43).…”