Comparison of kinematics and kinetics between unassisted and assisted maximum speed sprinting

Figures & data

Figure 1. Free body diagram with the average effective anteroposterior net mean force, effective vertical mean force, and the pulling mean force during maximum speed in control (normal) and assisted trials, and during matched (same) speed in the assisted trials. Units in newtons (N).

Table 1. Differences between the control (baseline) and assisted trials during the maximum speed phase. Significant difference specified as p value ≤ .050, indicated with bold text and an asterisk.

	Control Mean ± SD	Assisted Mean ± SD	MD (%)	Effect Size (CI)	P Value
Running Speed (m/s)	9.28 ± 0.25	10.14 ± 0.30	9.3	3.13 (2.80–3.47)	< .001*
Step Length (m)	2.08 ± 0.11	2.23 ± 0.14	7.3	1.20 (0.68–1.72)	< .001*
Step Frequency (Hz)	4.48 ± 0.24	4.57 ± 0.29	2.0	0.34 (0.00–0.68)	.045*
Contact Time (s)	0.100 ± 0.006	0.095 ± 0.007	−5.2	−0.80 (−3.21–1.61)	< .001*
Contact Length (m)	0.929 ± 0.052	0.963 ± 0.064	3.6	0.58 (−0.17–1.32)	< .001*
Flight Time (s)	0.124 ± 0.009	0.125 ± 0.009	0.8	0.11 (−1.91–2.14)	.552
Flight Length (m)	1.148 ± 0.088	1.265 ± 0.094	10.2	1.29 (0.59–1.99)	< .001*
Propulsive Mean Force (N/kg)	4.75 ± 0.32	4.54 ± 0.50	−4.3	−0.49 (−0.83 – −0.14)	.036*
Propulsive Impulse (Ns/kg)	0.27 ± 0.02	0.23 ± 0.02	−12.4	−1.62 (−3.32–0.09)	< .001*
Braking Mean Force (N/kg)	−4.17 ± 0.34	−5.60 ± 0.49	34.2	−3.39 (−3.86 – −2.92)	< .001*
Braking Impulse (Ns/kg)	−0.18 ± 0.02	−0.24 ± 0.03	32.5	−2.17 (−4.00 – −0.34)	< .001*
Anteroposterior Net Mean Force (N/kg)	0.82 ± 0.19	−0.10 ± 0.23	−112.0	−4.35 (−8.55 – −0.16)	< .001*
Anteroposterior Net Impulse (Ns/kg)	0.08 ± 0.02	−0.01 ± 0.02	−112.8	−4.49 (−17.58–8.61)	< .001*
Vertical Mean Force (N/kg)	22.43 ± 0.99	23.37 ± 0.92	4.2	0.98 (0.82–1.14)	< .001*
Vertical Impulse (Ns/kg)	2.25 ± 0.11	2.22 ± 0.15	−1.2	−0.20 (−0.68–0.28)	.277
Effective Vertical Mean Force (N/kg)	12.62 ± 0.99	13.56 ± 0.92	7.5	0.98 (0.78–1.19)	< .001*
Effective Vertical Impulse (Ns/kg)	1.25 ± 0.09	1.28 ± 0.09	1.9	0.27 (−0.37–0.90)	.235

MD = mean difference; CI = 95% lower – upper confidence interval range.

Table 2. Differences between the control (baseline) and assisted trials during the maximum speed phase in the control and the steps that matched this speed closest in the assisted trial. Significant difference specified as p value ≤ .050, indicated with bold text and an asterisk.

	Control Mean ± SD	Assisted Mean ± SD	MD (%)	Effect Size (CI)	P Value
Running Speed (m/s)	9.28 ± 0.25	9.28 ± 0.25	0.0	−0.01 (−0.24–0.23)	.935
Step Length (m)	2.08 ± 0.11	2.04 ± 0.10	−1.6	−0.30 (−0.81–0.20)	.064
Step Frequency (Hz)	4.48 ± 0.24	4.55 ± 0.20	1.5	0.31 (−0.03–0.64)	.070
Contact Time (s)	0.100 ± 0.006	0.100 ± 0.006	0.0	0.01 (−2.25–2.27)	.962
Contact Length (m)	0.929 ± 0.052	0.929 ± 0.051	0.0	0.00 (−0.74–0.74)	.989
Flight Time (s)	0.124 ± 0.009	0.120 ± 0.007	−2.8	−0.42 (−2.51–1.66)	.042*
Flight Length (m)	1.148 ± 0.088	1.115 ± 0.073	−2.8	−0.40 (−1.09–0.28)	.039*
Propulsive Mean Force (N/kg)	4.75 ± 0.32	4.90 ± 0.41	3.3	0.43 (0.10–0.75)	.042*
Propulsive Impulse (Ns/kg)	0.27 ± 0.02	0.29 ± 0.02	9.2	1.11 (−0.32–2.54)	< .001*
Braking Mean Force (N/kg)	−4.17 ± 0.34	−3.74 ± 0.40	−10.2	1.15 (0.75–1.55)	< .001*
Braking Impulse (Ns/kg)	−0.18 ± 0.02	−0.15 ± 0.02	−17.0	1.46 (−0.60–3.52)	< .001*
Anteroposterior Net Mean Force (N/kg)	0.82 ± 0.19	1.37 ± 0.26	67.2	2.44 (1.63–3.25)	< .001*
Anteroposterior Net Impulse (Ns/kg)	0.08 ± 0.02	0.14 ± 0.03	67.9	2.54 (−0.05–5.13)	< .001*
Vertical Mean Force (N/kg)	22.43 ± 0.99	22.17 ± 0.90	−1.1	−0.27 (−0.42 – −0.12)	.232
Vertical Impulse (Ns/kg)	2.25 ± 0.11	2.22 ± 0.09	−1.2	−0.25 (−0.73–0.23)	.212
Effective Vertical Mean Force (N/kg)	12.62 ± 0.99	12.36 ± 0.90	−2.0	−0.27 (−0.48 – −0.07)	.232
Effective Vertical Impulse (Ns/kg)	1.25 ± 0.09	1.23 ± 0.07	−2.1	−0.33 (−0.99–0.32)	.179

MD = mean difference; CI = 95% lower – upper confidence interval range.

Table 3. Correlation between the change (%) between trials (control vs. assisted) and performance change between trials (running speed) during the maximum speed phase. Significant difference specified as p value ≤ .050, indicated with bold text and an asterisk.

	Correlation Coefficient	P Value
Step Length	.090	.748
Step Frequency	.315	.253
Contact Time	−.565	.028*
Flight Time	−.141	.617
Propulsive Mean Force	.178	.525
Propulsive Impulse	−.072	.798
Braking Mean Force	.135	.633
Braking Impulse	−.022	.939
Anteroposterior Net Mean Force	−.022	.937
Anteroposterior Net Impulse	−.018	.948
Vertical Mean Force	.038	.894
Vertical Impulse	−.357	.192
Effective Vertical Mean Force	.031	.912
Effective Vertical Impulse	−.231	.408