Influence of Regular Post-Exercise Cold Water Immersion on Skeletal Muscle Microvascular Function Assessed By Near Infrared Spectroscopy
Ihsan, M and Watson, G and Buchheit, M and Hui, C and Govus, A and Abbiss, C, Influence of Regular Post-Exercise Cold Water Immersion on Skeletal Muscle Microvascular Function Assessed By Near Infrared Spectroscopy, Proceedings of the 18th Annual Congress of the European College of Sport Science, 26-29 June 2013, Barcelona, Spain, pp. 192. (2013) [Conference Extract]
Exercise training improves microvascular (MV) function via elevated nitric oxide production and/or ia an increase in capillary density (Lash et al. 1992). An acute post exercise cold water immersion (CWI) intervention enhanced the gene expression of vascular endothelial growth factor and nitric oxide (NO) synthase (NOS) (Ihsan et al. unpublished data). However, MV adaptations to regular post exercise CWI have yet to be investigated. The present study aimed to investigate the effect of training and regular post exercise CWI on MV function.
Eleven males performed 3 sessions/week of endurance training for 4 weeks. Following each session, subjects immersed one leg in a cold water bath (10°C; CWI) to the level of their gluteal fold for 15 min while the contra-lateral leg served as control (CON). Prior to, and following the training intervention, subjects performed a graded running test to exhaustion to determine their maximal oxygen uptake (VO2max) and aerobic speed (MAS). Additionally, MV function of the gastrocnemius was assessed in a randomised and counterbalanced order (i.e. CON & CWI limbs) using near infrared spectroscopy. While resting in a supine position, 5 min of popliteal artery occlusion was applied and upon cuff release, maximal changes in oxyhaemoglobin amplitude (O2Hbmax) response time associated with reaching O2Hbmax (RT) and 50% of O2Hbmax (RT50%), response rate (R-RATE; O2Hbmax/RT) and initial R-RATE (R-RATE50%; 50%-O2Hbmax/RT50%) were determined.
Results Exercise training improved VO2max (6.0±7.7%, p=0.026) and MAS (6.4±3.9%, p<0.001). While RT, RT50% and R-RATE were not influenced by training (p>0.05), R-RATE50% increased by 26±47% in the CON limb post training (p=0.037). Furthermore, O2Hbmax was increased in both the CON (18±21%, p=0.049) and CWI (20±34%, p=0.018). As a result, when expressed relative to pre O2Hbmax, significant training effects were observed in RT (CON; 55±13%, p<0.001, CWI; 49±26%, p<0.001) and R-RATE (CON; 55±13%, p<0.001, CWI; pre=49±26%, p<0.001). Yet, when expressed relative to pre O2Hbmax, improvements in RT50% (CON; 23±46%, p=0.003, CWI; pre=14±34%, p=0.263) and R-RATE50% (CON; 23±46%, p=0.045, CWI; pre=14±34%, p=0.407) was only significant in the CON limb.
The present findings suggest that regular post exercise CWI may suppress MV adaptations associated with the initial rate of O2Hb resaturation (RT50% and R-RATE50%). Somewhat contradictory to acute exposure (Ihsan et al. unpublished data), it is possible that regular CWI treatment may have attenuated exercise-induced NOS expression and hence flow-mediated MV function.