Introduction The running uphill is an intense activity, which can be performed in several training programs as an alternative way to work at high intensity, stressing the cardiovascular system. Precisely, sprinting on incline requires a considerable muscle activation of the lower limb, which affects central aerobic responses, as changes in heart rate (HR). (1,2). Therefore, the aim of the study was to investigate the HR variation during individuals sprint on different inclinations, based on two assumptions: I. HRs rise faster when sprinting on high slopes compared to the level. II. HR reaches higher peaks with increasing slope. Methods Ten amateurs soccer players carried out three “all-out” sprint lasting 6 seconds for each slope: level-7%-14%-18%. Every bout was separated by a complete recovery. Heart rate monitors (beat to beat) were used to record the time (milliseconds) among heartbeats before, during and after any sprint. Results Unlike what has been found during the sprints, heart rate assumed a different profile right after the effort between gradients. I. On slope of 18% heartbeats rose faster than what happened on the level reaching the peak value almost two second before (8368 ±451ms vs. 10291±462.2ms; p<0.05). II. Statistical differences were not highlighted between heart rate peaks in all of the gradients: level=154bpm, 7%=159bpm; 14%=155bpm, 18%=157bpm (p>0.05). Discussion In accordance with the first assumptions, results suggest that running on high slopes (>14%) produces a marked rising of the heartbeats which stress the cardiac system. A possible explanation could regard the fact that intense activity, such as sprinting uphill, increases the ratio of concentric to eccentric muscle activation involving a great metabolic expenditure (3). Although heart’s stroke volume is the parameter that mainly limits the aerobic performance (4), high rates of volume stroke (via the increase of heartbeats) are required to cover those demands of oxygen from the muscles paying for any anaerobic debt. In conclusion, it is reasonable to assume that sprinting uphill is one of the best ways of training due to its significant impact on the central cardiovascular system. References 1) Yokozawa T., Fujii N., Ae Michiyoshi. (2007). J Biomech, 40(15), 3467-3475. 2) Roberts T.J., Belliveau R.A. (2005). J Exp Biol, 208(10), 1963-1970. 3) Pringle J.S., Carter H., Doust J.H., Jones A.M. (2002). Eur J Appl Physiol, 88(1-2), 163-9. 4) Hoff J. (2005). J Sports Sci, 23(6), 573-582.
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