Biomechanics and subjective measures of recreational male runners in three shoes running outdoors: a randomised crossover study

Figures & data

Table 1. Characteristics of participants (n = 18) and shoes worn by participants.

Participants	Males
Age (y)	31.2 ± 10.5
Height (cm)	180.2 ± 6.0
Mass (kg)	81.6 ± 10.0
Leg length (mm)^†	912.1 ± 39.8
Running experience (years)	11.2 ± 8.1
5 km personal best time (min)	23.1 ± 2.1
Weekly training (km)	20.0 ± 12
Own shoe size (US sizing)	10.6 ± 1.0
Shoes^§	OWN	FLAT	VP4
Mass (g)	308 ± 42^F,V	153 ± 8^O,V	211 ± 12^O,F
Stack height (mm)	24.6 ± 7.2^F	13.0 ± 0^O,V	31.0 ± 0^F
Heel-to-toe drop (mm)	11.2 ± 5.7^F	1.0 ± 0^O,V	7.0 ± 0^F
Minimalist index (%)^‡	28 ± 15^F	88 ± 0^O,V	48 ± 0^F
Price (NZD)	156 ± 49^V	190 ± 0	380 ± 0^O,F

Data are mean ± standard deviation.

^†Greater trochanter to ground distance in a standing position barefoot.

^§Data from right shoes only (size: US 8.5–12).

^‡Minimalist index range: 0% (lowest) to 100% (highest) degree of minimalism.

^O,F,VSignificant difference during post-hoc paired t-test comparisons (p ≤ 0.05) vs. OWN, FLAT, and VP4, respectively.

FLAT, Saucony Endorphin Racer 2 road racing flat; OWN, runners own habitual running shoes; VP4, Nike Vaporfly 4%.

Figure 1. Overall study design (left diagram) and experimental process for each shoe (right diagram). ^FLAT and VP4 only. Abbreviations. FLAT, Saucony Endorphin Racer 2 racing flat. IMU, inertial measurement unit. OWN, own habitual running shoe. RUN-CAT, running shoe comfort assessment tool. VAS, visual analogue scale. VP4, Nike Vaporfly 4%.

Table 2. Variables (mean ± standard deviation) collected from the 1.1 km trial at a self-selected comfortable pace (slower) and a 400 m trial at a perceived 5 km pace (faster) ran by participants (n = 18).

Variable	Distance	OWN	FLAT	VP4	RM ANOVA (p value)
Overall speed (m/s)	1.1 km	3.57 ± 0.30	3.62 ± 0.35	3.65 ± 0.40	0.447
	400 m	4.18 ± 0.35	4.09 ± 0.36	4.15 ± 0.38	0.071
Optojump measurements
Speed (m/s)	1.1 km	3.66 ± 0.33^V,F	3.80 ± 0.38^O	3.78 ± 0.42^O	0.010
	400 m	4.30 ± 0.36	4.29 ± 0.46	4.34 ± 0.40	0.650
Cadence (steps/minute)	1.1 km	168.0 ± 7.5^F	171.1 ± 8.8^O,V	168.8 ± 8.5^F	0.005
	400 m	174.6 ± 8.8	176.2 ± 10.1	174.7 ± 9.1	0.080
Step length (cm)	1.1 km	130.9 ± 11.9	133.2 ± 11.2	134.5 ± 14.4	0.101
	400 m	148.1 ± 11.8	146.1 ± 14.4	149.3 ± 12.4	0.301
Flight time (s)	1.1 km	0.093 ± 0.019	0.097 ± 0.017	0.097 ± 0.021	0.133
	400 m	0.109 ± 0.016	0.107 ± 0.020	0.111 ± 0.018	0.415
Contact time (s)	1.1 km	0.265 ± 0.021^F	0.254 ± 0.022^O	0.259 ± 0.023	0.001
	400 m	0.236 ± 0.018	0.234 ± 0.022	0.234 ± 0.019	0.650
Propulsive phase (%)	1.1 km	45.3 ± 4.1^V	46.6 ± 3.7^V	43.1 ± 3.9^O,F	<0.001
	400 m	45.7 ± 3.5^V	47.2 ± 4.0^V	42.6 ± 3.8^O,F	<0.001
kvert (kN/m)	1.1 km	27.7 ± 3.5^F	29.2 ± 4.3^O,V	28.3 ± 3.6^F	<0.001
	400 m	31.5 ± 4.1	32.2 ± 4.3	31.8 ± 3.9	0.208
kleg (kN/m)	1.1 km	12.3 ± 2.7^F	12.9 ± 2.9^O,V	12.4 ± 2.6^F	0.019
	400 m	12.8 ± 2.9	13.2 ± 2.8	12.9 ± 2.8	0.250
Duty factor (%)	1.1 km	37.1 ± 2.5^F	36.1 ± 2.4^O	36.4 ± 2.8	0.026
	400 m	34.3 ± 2.1	34.3 ± 2.7	34.0 ± 2.3	0.575
2D camera data
Footstrike angle (°)	1.1 km	15.6 ± 6.4^F	12.4 ± 4.6^O,V	15.6 ± 6.2^F	0.003
	400 m	15.5 ± 5.8^F	12.2 ± 5.5^O,V	16.9 ± 5.1^F	<0.001
IMU sensor data
TRA (g)a	1.1 km	17.3 ± 3.4	19.0 ± 3.3	18.6 ± 4.2	0.134
	400 m	21.1 ± 4.4	22.2 ± 2.8	20.7 ± 3.7	0.421

^{F, O, V}Significant difference (p ≤ 0.05) vs. FLAT, OWN and VP4 during post-hoc comparisons, respectively. Significant differences (p ≤ 0.05) are in bold.

^aMissing data from 4 participants.

2D, two-dimensional; FLAT, Saucony Endorphin Racer 2 road racing flat; IMU, inertial measurement unit; k_leg, leg stiffness; k_vert, vertical stiffness; OWN, runners own habitual running shoes; RM ANOVA, repeated measures analysis of variance; TRA, tibial resultant acceleration; VP4, Nike Vaporfly 4%.

Table 3. Visual analogue scale (0–100 mm scale, mean ± standard deviation) scores on comfort, shoe properties, and overall running experience of participants (n = 18).

Characteristics	OWN	FLAT	VP4	RM ANOVA (p value)
Comfort VAS
Predicted comfort	–	34.3 ± 21.8	43.5 ± 20.1	0.136
Acute comfort	66.2 ± 16.7^F	42.9 ± 21.7^O,V	60.1 ± 23.0 ^F	0.003
Slow speed comfort	65.2 ± 14.9^F	42.8 ± 24.4^O,V	59.4 ± 24.3^F	0.003
Fast speed comfort	64.7 ± 16.8	51.3 ± 23.1	57.4 ± 25.7	0.149
Shoe properties VAS
Heel cushioning*	48.8 ± 14.3^F,V	25.6 ± 14.9^O,V	68.4 ± 17.8^O,F	<0.001
Forefoot cushioning*	45.4 ± 11.0^F	31.5 ± 19.9^O,V	52.9 ± 20.1^F	<0.001
Forefoot flexibility*	53.4 ± 14.4^V	58.4 ± 14.9^V	38.4 ± 14.5^O,F	<0.001
Shoe stability*	46.4 ± 11.7	38.3 ± 16.7	43.4 ± 17.4	0.310
RUN-CAT **	81.3 ± 10.8^V,F	64.2 ± 23.1^O	70.8 ± 19.4^O	0.031
Shoe stiffness*	39.4 ± 14.1^V	37.8 ± 18.2^V	58.1 ± 11.7^O,F	<0.001
Technical features*	38.0 ± 13.0^V, b	34.3 ± 11.0^V	55.5 ± 15.4^O, F	<0.001
Shoe weight*	58.7 ± 9.7^F, b	41.7 ± 8.9^O, V	50.9 ± 12.9^F	<0.001
Overall running experience VAS
Pleasure/displeasure	59.1 ± 15.7^b	40.0 ± 25.3	52.1 ± 26.6	0.068
Easier/harder	55.9 ± 14.0^b	44.4 ± 22.7	50.8 ± 23.1	0.237
Performance (worse/improved)	49.4 ± 9.7^b	47.6 ± 19.5	52.8 ± 23.5	0.740
Injury risk (lower/higher)	46.4 ± 20.0^F, V, b	70.1 ± 16.4^O	60.2 ± 17.7^O	0.002

^F,O,VSignificant difference during post-hoc comparisons (p ≤ 0.05) vs. FLAT, OWN and VP4, respectively. Significant differences (p ≤ 0.05) are in bold.

^bMissing data from 1 participant.

*Midpoint (50 mm) represents ideal, 0 mm indicates an absence of the property and 100 mm indicates too much of a property.

**RUN-CAT weighted average of four preceding properties, where 100 represents ideal.

FLAT, Saucony Endorphin Racer 2 road racing flat; OWN, runners own habitual running shoes; RUN-CAT, running shoe comfort assessment tool; VAS, visual analogue scale; VP4, Nike Vaporfly 4%.

Table 4. Ranking of shoes by participants (n = 18) values are count (percentage %).

Shoe	Rank 1 (most preferred)	Rank 2	Rank 3 (least preferred)	Friedman (p value)
Comfort at slow speed				0.011
Own	10 (55.6%)	7 (38.9%)	1 (5.6%)
Flat	1 (5.6%)	7 (38.9%)	10 (55.6%)
VP4	7 (38.9%)	4 (22.2%)	7 (38.9%)
Comfort at fast speed				0.607
Own	3 (16.7%)	12 (66.7%)	3 (16.7%)
Flat	5 (27.8%)	1 (5.6%)	7 (38.9%)
VP4	10 (55.6%)	5 (27.8%)	8 (44.4%)
Race performance				0.678
Own	6 (33.3%)	9 (50%)	3 (16.7%)
Flat	5 (27.8%)	6 (33.3%)	7 (38.9%)
VP4	7 (38.9%)	3 (16.7%)	8 (44.4%)
Lowest injury risk				<0.001
Own	14 (77.8%)	4 (22.2%)	0 (0%)
Flat	1 (5.6%)	2 (11.1%)	15 (83.3%)
VP4	3 (16.7%)	12 (66.7%)	3 (16.7%)

Notes. Significant differences (p ≤ 0.05) in rankings using Freidman and Goodness-of-Fit in post-hoc tests are in bold.

FLAT, Saucony Endorphin Racer 2 road racing flat; OWN, runners own habitual running shoes; VP4, Nike Vaporfly 4%.

Table 5. Repeated measures correlations between comfort measures and subjective and biomechanical measures of data from 18 participants.

	Predicted comfort	Acute comfort	Slow speed comfort	Fast speed comfort	RUN-CAT
Comfort VAS
Predicted comfort	1.000	–	–	–	–
Acute comfort	0.376	1.000	–	–	–
Slow speed comfort	0.270	0.679	1.000	–	–
Fast speed comfort	0.369	0.534	0.715	1.000	–
Shoe properties VAS
Heel cushioning*	−0.003	0.400	0.451	0.567	0.832
Forefoot cushioning*	−0.075	0.371	0.669	0.636	0.901
Forefoot flexibility*	0.386	0.264	0.322	0.595	0.438
Stability*	−0.160	0.284	0.524	0.391	0.791
RUN-CAT**	0.004	0.436	0.673	0.720	1.000
Shoe stiffness*	0.315	0.352	0.429	0.540	0.431
Technical features*	0.003	−0.164	−0.063	0.014	0.184
Shoe weight*	0.053	0.158	0.006	0.153	0.095
Overall running experience VAS
Pleasure/displeasure	0.481	0.534	0.647	0.776	0.714
Easier/harder	0.511	0.402	0.560	0.757	0.582
Performance (worse/improved)	0.367	0.175	0.171	0.468	0.400
Injury risk (lower/higher)	0.014	−0.567	−0.564	−0.396	−0.579
Biomechanical measures
Overall speed (1.1 km)	0.154	0.070	0.026	0.095	0.157
Overall speed (400 m)	0.045	0.131	0.078	0.189	0.260
Cadence	−0.494	−0.236	−0.117	−0.160	−0.127
Step length	0.157	0.202	0.053	0.353	0.011
Flight time	0.109	0.137	0.066	0.275	0.043
Contact time	0.228	0.018	−0.013	−0.146	0.043
Propulsive phase	−0.128	−0.307	−0.217	−0.095	−0.099
kvert	−0.436	−0.135	−0.103	0.026	−0.123
kleg	−0.308	−0.159	−0.055	−0.098	−0.066
Duty factor	0.157	0.027	0.117	−0.145	0.029
Footstrike angle	0.018	0.237	0.162	0.108	0.223
TRA	−0.462	−0.243	−0.214	−0.235	0.054

Notes. Significant correlations (p ≤ 0.05) that are moderate (|r| ≥ 0.30) or large (|r| ≥ 0.50) are deemed meaningful and shown in bold.

*Original scores where the midpoint (50 mm) represents ideal were rescaled before exploratory analysis so that 0 mm indicates ‘not ideal’ and 100 mm presents ‘most ideal’.

**RUN-CAT weighted average of four preceding properties, where 0 represents not ideal and 100 represents most ideal.

k_leg, leg stiffness; k_vert, vertical stiffness; RUN-CAT, running shoe comfort assessment tool; TRA, tibial resultant acceleration; VAS, visual analogue scale.

Data availability statement

The data that support the findings of this study are openly available in OSF at http://doi.org/10.17605/OSF.IO/A64N5 (Hébert-Losier, 2023).