1. O2 Consumption (mL⋅kg-1⋅min-1) Heart Rate (beats⋅min-1)
The Effects of Barefoot Running on
5 km Running Performance.
Ashley Warner1, Grant Abt2, Phil Marshall2.
1School of Sport & Exercise, University of Gloucestershire, UK
2Department of Sport, Health and Exercise Science, The University of Hull, UK
Table 2. Physiological and perceptual responses during the ventilatory threshold test.
Barefoot
Hybrid
Shod
O2 Consumption (mL⋅kg-1⋅min-1)
6 km⋅h-1
18±2
17±4
19±3
VT1
26±4
25±3
25±5
VT2
36±6
36±3
Exhaustion
40±6
41±6
40±5
Blood Lactate (mM⋅L-1)
1.7±0.6
1.7±0.7
1.7±0.5
1.1±0.6
2.0±0.4
2.6±1.0
5.8±1.3
5.6±1.2
6.2±1.3
9.3±1.9
9.4±2.0
9.9±1.9
Heart Rate (beats⋅min-1)
114±15
112±11
110±17
137±8
134±11
136±13
164±6
164±8
166±8
172±8
171±10
176±7
RPE (AU)
6.8±0.8
6.7±0.8
6.6±0.5
9.5±1.7
9.7±1.9
9.6±1.5
14.0±1.3
14.0±1.2
16.6±0.5
16.7±0.8
16.8±0.1
Introduction
An important determinant in successful long distance running is economy (Lucia et al. 2006). Long distance runners who have better economy can run at a faster speed with a lower oxygen cost compared to those with a low running economy (Saunders et al., 2004).
Barefoot running has been reported to reduce the oxygen cost of running (Shorten et al., 2000, Hanson et al., 2010). The mechanisms responsible for this are unclear, however, there are two main theories: (1) the forefoot landing technique observed in barefoot running, which results in less extension at the knee and reduced flexion at the hip during the swing phase leading to a reduced breaking phase at contact (Perl et al., 2012), or (2) the elimination of shoe mass (Hanson et al., 2010).
The aims of the current study were to: (1) determine if running performance is affected by running barefoot, and (2) if shoe mass or running technique (forefoot landing pattern) is responsible for alterations in running economy.
Methods
Following institutional ethics approval, 10 participants (8 male 2 female) were recruited. Inclusion criteria included: (1) a minimum of six months barefoot running experience, and (2) a minimum competitive distance of 5 km in the previous three months. Participants completed a trial run on a motorised treadmill prior to the main trials to assess their forefoot landing pattern. If they did not forefoot strike with a minimum of 85% of foot landings during a two minute self-paced run they were excluded from the study. Forefoot strike pattern was assessed via video analysis (Sony DCR-VX1000E Camcorder, Sony UK).
As part of the initial baseline testing, maximal oxygen uptake (VO2MAX) was measured on a motorised treadmill (Woodway PPS 55sport I, Weil an rhein, Germany) (Tenaka et al., 2001), from which speed at the first (VT1) and second (VT2) ventilatory thresholds were identified (Lucia et al. 2000).
For the main trials participants performed each of the three experimental conditions: (1) barefoot (2) shod (3) hybrid (forefoot landing in shod conditions) in a randomised crossover design. The following tests were conducted:
Ventilatory threshold: Participants completed three, four minute stages. Stage 1 was completed at VT1 speed, stage 2 at VT2 speed, and stage 3 was an incremental stage where treadmill speed increased by 0.2 km⋅h-1 every 12 seconds from VT2 until volitional exhaustion. Heart rate was measured continuously during each stage. Blood lactate and RPE were measured at the completion of each stage.
5 km running performance: Participants completed a self-paced 5 km ‘race pace’ performance (Jones and Doust, 1996) on a motorised treadmill.
Ground reaction force: Participants ran across a 20 m runway, split into 5 m zones. The final 5 m zone was timed with electronic gates (SMARTSPEED, Queensland, Australia). A force platform (AMTI, Watertown, Massachusetts USA) situated at 17.5 m recorded ground reaction force data. Participants performed trials in all three conditions at both VT1 and VT2 speed. For trials to be deemed acceptable two criteria had to be met: (1) participant’s foot landings had to make a full clean contact in the middle of the force plate, and (2) all split times between timing gates had to be within 0.1 s of a pre-calculated time that corresponded to the runner’s VT speed.
Figure 1. (top) Cohen’s d ± 90% CI for performance, physiological & perceptual responses during the VT test; (bottom) Cohen’s d ± 90% CI for peak GRF during the VT test.
Statistical analysis was performed using the methods of Hopkins et al. (2009). The between condition pooled standard deviation was used to calculate Cohen’s d effect size statistic and 90% confidence intervals. Effect size magnitudes were defined as: (trivial), (small), (moderate), (large), and ≥2.0 (very large).
Conclusion
The major findings are:
Running technique and/or footwear may affect running performance without a subsequent increase in perceived exertion or physiological response.
May be evidence to suggest that running technique plays a more pivotal role in running economy than shoe weight.
Still unclear whether running barefoot improves performance or whether shod running degrades performance in experienced barefoot runners.
Results
Results indicated a small reduction in time to complete 5 km in favour of the barefoot trial compared to the shod condition, and a small reduction in time to complete the 5 km trial in favour of the barefoot condition when compared to the hybrid condition. There were trivial differences between time to complete the 5 km trials when comparing hybrid against shod. The differences in oxygen cost across all conditions were likely trivial or unclear.
References
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PERL, D. P., DAOUD, A. I. & LIEBERMAN, D. E Effects of Footwear and Strike Type on Running Economy. Medicine and Science in Sports and Exercise, 44,
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Table 1. Performance, physiological, and perceptual responses during the 5 km time trial.
Barefoot
Hybrid
Shod
Time to complete (min)
24.2±3.2
26.2±4.0
26.5±2.9
Heart Rate (beats⋅min-1)
170±10
165±12
169±10
RPE (AU)
14.3±1.2
14.0±1.0
14.6±0.8