Repeated sprint cycling performance is not enhanced by ischaemic preconditioning or muscle heating strategies

Figures & data

Figure 1. Schematic of experimental protocol detailing the order of events on each laboratory visit.

Figure 2. (a) Typical NIRS muscle oxygenation data during 10 × 6-s all-out sprints and (b), an example of a single 6-s sprint, followed by a 24-s recovery. Assessment of NIRS data during sprints was obtained from the first 7 s of effort, accounting for any additional pedal strokes. Deoxygenation amplitude (Deoxy_AMP) and slope (Deoxy_slope) were calculated from the maximal (TOI_max) and minimal (TOI_min) values (horizontal solid lines). Time Delay (TD) was defined as the time (s) from post-sprint to the beginning of muscle reoxygenation. Mean TD was 2.11 ± 0.95 s. Recovery amplitude (Reoxy_AMP) and rate (Reoxy_slope) were calculated from maximal (recTOI_max) and minimal (recTOI_min) values (horizontal dashed lines). TOI; Tissue oxygenation index, S1-10; Sprint number.

Table I. Peak and average power comparisons between conditions, accompanied with the likelihood of “beneficial”, “trivial” or “unlikely” performance outcomes.

Condition	Mean change (W)	90% CI lower (W)	90% CI upper (W)	% chance beneficial	% chance trivial	% chance Unlikely	Inference	P value
Peak power output
IPC vs SHAM	5.6	−14	25.7	68.4	1.2	30.4	Unclear	0.62
IPC vs HEAT	2.7	−18.1	23.6	57.9	1.2	40.9	Unclear	0.83
IPC vs IPC + HEAT	3.9	−16.9	24.7	61.9	1.2	36.9	Unclear	0.75
HEAT vs IPC + HEAT	1.2	−19.6	22.8	53.3	1.3	45.3	Unclear	0.92
HEAT vs SHAM	2	−18.8	22.8	55.9	1.3	42.9	Unclear	0.87
IPC + HEAT vs SHAM	0.8	−20	21.6	51.9	1.2	46.9	Unclear	0.95
Average power output
IPC vs SHAM	12.2	−6.7	31	85.6	0.7	13.6	Unclear	0.28
IPC vs HEAT	2.8	−16.1	21.6	58.8	1.3	39.8	Unclear	0.81
IPC vs IPC + HEAT	7.4	−11.4	26.3	73.9	1.1	24.9	Unclear	0.51
HEAT vs IPC + HEAT	4.7	−14.2	23.6	65.4	1.3	33.4	Unclear	0.68
HEAT vs SHAM	9.4	−9.4	28.3	79.5	1	19.5	Unclear	0.4
IPC + HEAT vs SHAM	4.7	−14.1	18.9	65.8	1.3	32.8	Unclear	0.67

Table II. Muscle NIRS (deoxygenation [Deoxy_AMP (%) and Deoxy_slope (% s⁻¹)] and reoxygenation [Reoxy_AMP (%) and Reoxy_slope (% s⁻¹)] characteristics) and EMG (RMS% activity) for 10 × 6-s repeated sprints between conditions.

		Condition
		IPC	HEAT	IPC + HEAT	SHAM	P value (condition)
NIRS	DeoxyAMP (%)	15 ± 7	18 ± 8	19 ± 9	13 ± 4	0.11
	Deoxyslope (% s^−1)	3 ± 1	3 ± 1	3 ± 1	2 ± 1	0.08
	ReoxyAMP (%)	8 ± 2	8 ± 3	11 ± 5	8 ± 3	0.18
	Reoxyslope (% s^−1)	1.1 ± 1	1.4 ± 1	1.5 ± 1	1 ± 0	0.18
EMG	VL (RMS%)	85 ± 3	78 ± 3	82 ± 3	84 ± 3	0.55
	RF (RMS%)	80 ± 4	80 ± 2	78 ± 5	78 ± 4	0.9
	BF (RMS%)	75 ± 4	76 ± 6	74 ± 4	75 ± 5	0.87