Jamie K. Pugh

Acute molecular responses to concurrent resistance and high‐intensity interval exercise in untrained skeletal muscle

Concurrent training involving resistance and endurance exercise may augment the benefits of single‐mode training for the purpose of improving health. However, muscle adaptations, associated with resistance exercise, may be blunted by a subsequent bout of endurance exercise, via molecular interference. High‐intensity interval training (HIIT), generating similar adaptations to endurance exercise, may offer an alternative exercise mode to traditional endurance exercise. This study examined the influence of an acute HIIT session on the molecular responses following resistance exercise in untrained skeletal muscle. Ten male participants performed resistance exercise (4 × 8 leg extensions, 70% 1RM, (RE)) or RE followed by HIIT (10 × 1 min at 90% HRmax, (RE+HIIT)). Muscle biopsies were collected from the vastus lateralis before, 2 and 6 h post‐RE to determine intramuscular protein phosphorylation and mRNA responses. Phosphorylation of Akt (Ser473) decreased at 6 h in both trials (P < 0.05). Phosphorylation of mTOR (Ser2448) was higher in RE+HIIT (P < 0.05). All PGC‐1α mRNA variants increased at 2 h in RE+HIIT with PGC‐1α and PGC‐1α‐ex1b remaining elevated at 6 h, whereas RE‐induced increases at 2 and 6 h for PGC‐1α‐ex1b only (P < 0.05). Myostatin expression decreased at 2 and 6 h in both trials (P < 0.05). MuRF‐1 was elevated in RE+HIIT versus RE at 2 and 6 h (P < 0.05). Atrogin‐1 was lower at 2 h, with FOXO3A downregulated at 6 h (P < 0.05). These data do not support the existence of an acute interference effect on protein signaling and mRNA expression, and suggest that HIIT may be an alternative to endurance exercise when performed after resistance exercise in the same training session to optimize adaptations.

Comments on Crosstalk 26: Highintensity interval trainingdoes/does not have a role in riskreduction or treatment ofdisease. Personalised exercise – timeto HIIT the right balance.

This is the peer reviewed version of the following article: PUGH, J.K. and FAULKNER, S.H., 2016. Comments on Crosstalk 26: High intensity interval training does/does not have a role in risk reduction or treatment of disease. Personalised exercise – time to HIIT the right balance. Journal of Physiology, 593(24), pp. 5215–5404., which has been published in final form at http://dx.doi.org/10.1113/JP271041. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. It is a comment on the original article and can be found in supporting information.

The Effect of High Intensity Interval Exercise on Postprandial Triacylglycerol and Leukocyte Activation – Monitored for 48h Post Exercise

Postprandial phenomenon are thought to contribute to atherogenesis alongside activation of the immune system. A single bout of high intensity interval exercise attenuates postprandial triacylglycerol (TG), although the longevity and mechanisms underlying this observation are unknown. The aims of this study were to determine whether this attenuation in postprandial TG remained 2 days after high intensity interval exercise, to monitor markers of leukocyte activation and investigate the underlying mechanisms. Eight young men each completed two three day trials. On day 1: subjects rested (Control) or performed 5 x 30 s maximal sprints (high intensity interval exercise). On day 2 and 3 subjects consumed high fat meals for breakfast and 3 h later for lunch. Blood samples were taken at various times and analysed for TG, glucose and TG-rich lipoprotein (TRL)-bound LPL-dependent TRL-TG hydrolysis (LTTH). Flow cytometry was used to evaluate granulocyte, monocyte and lymphocyte CD11b and CD36 expression. On day 2 after high intensity interval exercise TG area under the curve was lower (P<0.05) (7.46±1.53 mmol/l/7h) compared to the control trial (9.47±3.04 mmol/l/7h) with no differences during day 3 of the trial. LTTH activity was higher (P<0.05) after high intensity interval exercise, at 2 hours of day 2, compared to control. Granulocyte, monocyte and lymphocyte CD11b expression increased with time over day 2 and 3 of the study (P<0.0001). Lymphocyte and monocyte CD36 expression decreased with time over day 2 and 3 (P<0.05). There were no differences between trials in CD11b and CD36 expression on any leukocytes. A single session of high intensity interval exercise attenuated postprandial TG on day 2 of the study, with this effect abolished by day 3.The reduction in postprandial TG was associated with an increase in LTTH. High intensity interval exercise had no effect on postprandial responses of CD11b or CD36.

Do overweight and obese individuals demonstrate impaired thermoregulatory adaptation to six weeks of studio cycling training: A pilot study.

High intensity interval training (HIIT) is effective at improving health markers in groups at risk of cardiovascular and metabolic disease. Studio cycling may offer a platform for HIIT in the community, however little is know about how increased adiposity influences thermal control during HIIT and the effect this may have on overweight patients who are new to exercise. The purpose of this pilot study was to investigate the thermal adaptation in response to studio based group HIIT in sedentary overweight adults.