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Preferred walking speed on rough terrain: is it all about energetics?
Open accessPublished version of a preprint
Abstract
Humans have evolved the ability to walk very efficiently. Further, humans prefer to walk at speeds that approximately minimize their metabolic energy expenditure per unit distance (i.e. gross cost of transport, COT). This has been found in a variety of population groups and other species. However, these studies were mostly performed on smooth, level ground or on treadmills. We hypothesized that the objective function for walking is more complex than only minimizing the COT. To test this idea, we compared the preferred speeds and the relationships between COT and speed for people walking on both a smooth, level floor and a rough, natural terrain trail. Rough terrain presumably introduces other factors, such as stability, to the objective function. 10 healthy men walked on both a straight, flat, smooth floor and on an outdoor trail strewn with rocks and boulders. In both locations, subjects performed 5-7 trials at different speeds relative to their preferred speed. The COT-speed relationships were similarly U-shaped for both surfaces, but the COT values on rough terrain were approximately 115% greater. On the smooth surface, the preferred speed (1.24+/−0.17 m/sec) was found to be statistically not different (p-value =0.09) than the speed that minimized COT (1.34 +/− 0.03 m/sec). On rough terrain, the preferred speed (1.07+/−0.05 m/sec) was slower than the COT minimum speed (1.13 +/− 0.07 m/sec) and was statistical significant (p-value=0.02). Since near the optimum speed the COT function is very shallow, these changes in speed result in small change in COT (0.5%). It appears that the objective function for speed preference when walking on rough terrain includes COT and additional factors such as stability.
Overview
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Written from the paper’s full text.
TL;DR
This study compared preferred walking speed and metabolic cost of transport (COT) on a smooth, level floor versus a natural rough trail. On rough terrain, preferred speed was significantly slower than the COT-minimizing speed, suggesting walking-speed preference is not explained by energetics alone.
Key findings
- COT–speed relationships were U-shaped on both surfaces, but COT on rough terrain was approximately 115% greater than on the smooth floor.
- On the smooth floor, preferred speed (1.24±0.17 m s⁻¹) was not statistically different from the COT-minimizing speed (1.34±0.03 m s⁻¹; P=0.09).
- On rough terrain, preferred speed (1.07±0.05 m s⁻¹) was significantly slower than the COT-minimizing speed (1.13±0.07 m s⁻¹; P=0.02).
- Because the COT function is shallow near the optimum, these speed differences changed COT by only 0.8% on the smooth floor and 0.3% on rough terrain; normalized COT–speed curves were similar despite a significant Chow test (P=0.003; meaningful coefficient 0.84).
Methods
- Ten healthy men (body mass 75.10±11.64 kg, height 1.82±0.07 m, age 27.5±1.6 years) walked on a 44.0 m smooth, level concrete floor and a 67.0 m rough outdoor trail with rocks and boulders (straight-line distance 60.3 m; maximum elevation amplitude <2 m).
- Subjects performed trials at preferred, very slow (~50%), slow (~75%), fast (~120–150%), and maximum (~140–190%) speeds; six trials on smooth floor and seven on rough terrain, each 7–9 min, with 5-min rests. Only the second rough-terrain session was analyzed to avoid learning effects.
- Metabolic rate was measured with a portable K4b2 indirect calorimetry system; COT was calculated as MR/(speed×body mass). Only RER<1 trials were analyzed, steady-state measurements were taken at least 3 min after start, and full out-and-back laps were averaged. Linear mixed models with polynomial orders 1–4 were selected by BIC, and Chow tests, paired t-tests, and a meaningful coefficient were used for comparisons.
Limitations
- The authors state they did not model or measure stability on rough terrain as a function of speed, and they do not claim their proposed objective function is the only possible explanation; slower rough-terrain walking might also reflect the need for more accurate foot placement.
- The sample was small and restricted to ten healthy men, so findings may not generalize to women, older adults, or clinical populations (evident from the text).
- The rough-terrain condition required practice and only the second session was used; trials were excluded for RER>1, a fall, and recording failure, and the specific trail may limit generalization to other rough surfaces (evident from the text).
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1 of 59 cited sources checked · 1 supported · 0 flagged
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“On rough terrain, the preferred speed (1.07±0.05m s -1 ) was significantly slower than the COT minimum speed (1.13±0.07m s -1 ; P=0.02).”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesA result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The COT-speed relationships were similarly U-shaped for both surfaces, but the COT values on rough terrain were approximately 115% greater.”
- Also stated in: § COT · plain
“For both surfaces, the best fit to the data (i.e.lowest BIC; Appendix 2, Table A2) was of the form COT(s)=bs 2 +cs+d”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes- Also stated in: § COT · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“but the COT values on rough terrain were approximately 115% greater.”
- Also stated in: § COT · plain
“We found that the average COT values for the rough terrain were approximately 115% greater than those obtained for the smooth floor condition.”
- Also stated in: § DISCUSSION · plain
“The COT for the rough terrain was considerably greater (∼115%) than for smooth, level walking”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes- Also stated in: § COT · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“On the smooth surface, the preferred speed (1.24±0.17m s -1 ) was not found to be statistically different (P=0.09)than the speed that minimized COT (1.34±0.03m s -1 ).”
- Also stated in: § COT · plain
“For the smooth floor condition, a paired t-test showed no significant difference between the preferred and optimal speeds (P=0.09)”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passes- Also stated in: § COT · plain
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Our results revealed that, similar to past studies that studied COT on smooth, level ground and treadmills (e.g.Ralston, 1958;Zarrugh et al., 1974), the subjects' preferred speeds on both surfaces were close to the speeds that minimized COT.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesA claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“The function describing the dependence of metabolic rate on speed for the smooth, level floor condition in the present study is similar to prediction equations developed in previous studies (Givoni and Goldman, 1971;Ralston, 1958;Zarrugh et al., 1974;Pandolf et al., 1977).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesA result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“On both surfaces, the preferred speed was close to the respective energetic optimum speed.”
§ Preferred walking speed on rough terrain: is it all about energetics? > COT
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesA result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The preferred walking speed (averaged across all subjects) on rough terrain of 1.07±0.05m s -1 (mean±s.d.) was approximately 14% slower than the preferred walking speed of 1.24±0.17m s -1 on the smooth floor (Fig. 3).”
§ Preferred walking speed on rough terrain: is it all about energetics? > COT
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In the paper
“However, the COT functions in Fig. 3 are very shallow near the optimum speed, such that the difference between the preferred speed and optimal speed caused a change in COT value of only 0.8% for the smooth floor and 0.3% for the rough terrain.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
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In the paper
“We found that steady-state rates of energy expenditure were obtained after approximately 1.5-2 min.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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- It may state two separate claims as one. 22
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- Probably not a substantial claim. 23
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In the paper
“For example, it has been shown that step frequency (Zarrugh et al., 1974), step length (Umberger and Martin, 2007), step width (Donelan et al., 2001) and speed (Zarrugh et al., 1974) are all chosen to minimize energy expenditure.”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
- Not checked — no full text of the sourcecites Zarrugh et al., 1974 source
- Not checked — no full text of the sourcecites Umberger and Martin, 2007 source
- Supportedcites Donelan et al., 2001 source
Donelan et al. are cited for step width, not for step frequency, step length, or speed. The Results (section 3) report that preferred step width was not statistically different from the width that minimized metabolic cost, and the Discussion (section 4) concludes that humans appear to prefer a metabolically minimizing step width. (LLM, conf=0.94)
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In a pilot study, we found that there was a learning effect and that it took approximately 25 min of practice before the COT stabilized.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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In the paper
“The actual walking path was relatively straight but had some small elevation and left-right deviations.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Protocol
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“This was tested using the polynomials of orders 2 to 4, yet BIC values were higher, meaning the fit was worse.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Additional information
What the sources say
- Not checked — no full text of the sourcecites Ralston, 1958 source
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We measured the changes in elevation along the trail and found that the maximum elevation amplitude was less than 2 m (Fig. 1A).”
§ Preferred walking speed on rough terrain: is it all about energetics? > Protocol
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The preferred speed on the smooth floor was, on average, 8% slower than the optimum speed, but the difference was not statistically significant (P=0.09).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
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In the paper
“Note that although the Pandolf et al. (1977) equation is used more commonly, the prediction equation of Givoni and Goldman (1971) had the best match to our rough terrain data (lowest RMSE).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The trail comprised some naturally scattered rocks and boulders (Fig. 1B; for a short video of a subject walking, see Movie 1).”
§ Preferred walking speed on rough terrain: is it all about energetics? > Protocol
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In the paper
“In a pilot study, we found that this protocol accelerated learning and reduced adaptation time.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Yet, the meaningful coefficient (Eqn 4) was only 0.84, which means that the average difference between the model is smaller than the average error in the models predictions.”
§ Preferred walking speed on rough terrain: is it all about energetics? > COT change as a function of speed
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In the paper
“This procedure produced terrain factors of 1.9 and 3.1 for Givoni and Goldman (1971) and Pandolf et al. (1977), respectively.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The metabolically optimal average speed (the speed that minimizes the fitted COT functions) was 1.34±0.04m s -1 on the smooth floor and 1.13±0.07m s -1 on rough terrain.”
§ Preferred walking speed on rough terrain: is it all about energetics? > COT
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In the paper
“Humans have evolved the ability to walk very efficiently.”
- Also stated in: § INTRODUCTION · plain
“Humans have evolved the ability to walk very efficiently.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
What the sources say
- Not matchedcites Alexander, 2003
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
- Also stated in: § INTRODUCTION · plain
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Givoni and Goldman (1971) and Pandolf et al. (1977) developed prediction equations for the metabolic cost of load-carrying while walking on different terrains and slopes.”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
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In the paper
“Over generations, our bodies have evolved muscular and skeletal systems well suited to locomotion (Alexander, 2003).”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
- Not matchedcites Alexander, 2003
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
- Not matched
In the paper
“However, without a guide, their preferred walking speed is slower and is unlikely to correspond to their COT minimum.”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
- Not checked — no full text of the sourcecites Clark-Carter et al. (1986) source
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Because near the optimum speed the COT function is very shallow, these changes in speed result in a small change in COT (0.5%).”
§ Preferred walking speed on rough terrain: is it all about energetics? > Abstract
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In the paper
“Kalantarov et al. (2018) found that pedestrians crossing a street increased their walking speed when the time gap between cars was smaller.”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
- Not checked — no full text of the sourcecites Kalantarov et al. (2018) source
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“A recent study examined the metabolic cost of walking on a treadmill that imitates uneven terrain (Voloshina and Ferris, 2013).”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
- Not matchedcites Voloshina and Ferris, 2013
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
- Not matched
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Further, we learn and choose to walk in a way that minimizes our metabolic energy expenditure (Ralston, 1958;Zarrugh et al., 1974).”
§ Preferred walking speed on rough terrain: is it all about energetics? > INTRODUCTION
What the sources say
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In the paper
“Therefore, we only analyzed measurements of metabolic rate that were obtained at least 3 min after the start time.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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In the paper
“This allowed us to avoid the problem of over-fitting the data (e.g.fitting a third-order polynomial to six data points).”
§ Preferred walking speed on rough terrain: is it all about energetics? > Additional information
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
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In the paper
“Therefore, to eliminate the possibility of acquiring data during this learning period, subjects completed two rough terrain sessions during which they performed the full experimental protocol.For our analysis, we used only the second session data.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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In the paper
“The protocol was inspired by Selinger et al. (2015), who studied humans walking with novel exoskeletons and found that in order to find the optimal step frequency, which minimized their metabolic rate, subjects had to carry out an exploratory session in which they walked at fast and slow step frequencies.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
What the sources say
- Not checked — no full text of the sourcecites Selinger et al. (2015) source
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In the paper
“Every day and before each trial, the turbine was calibrated using a standard authorized calibration gas mixture and a volume pump.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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In the paper
“and/or other stability-related issues.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
Strength:hedged· not yet calibratedCausal:conditional· not yet calibratedTests✓ Asserted: passes✗ Checkable: fails✗ Load-bearing: fails✗ Based: failsProbably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
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In the paper
“It is worth noting that other species, for example wildebeest (Pennycuick, 1975), elephants (Langman et al., 1995) and horses (Hoyt and Taylor, 1981), also exhibit preferred terrestrial locomotion speeds within each gait.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“and their localized effort, which can be reflected in electromyographic recordings (Korol et al., 2014(Korol et al., , 2017)).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedCausal:correlational· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
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In the paper
“To ensure that the metabolic energy was primarily generated via aerobic metabolism, only trials with a respiratory exchange ratio (RER) of less than 1.00 were analyzed.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Data analysis
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In the paper
“To eliminate the effects of local terrain variation, we averaged metabolic rate values over full out-and-back laps.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
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None of the sources cited for this claim have been checked yet.
In the paper
“shorter step lengths and wider step widths (Donelan et al., 2001;Zarrugh et al., 1974)”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedCausal:conditional· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesThe quote only partly states this claim.
In the paper
“In our case, the fluctuations in walking speed were significantly smaller and probably had a negligible effect on metabolic expenditure.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Experimental procedure
What the sources say
- Not matchedcites Seethapathi and Srinivasan (2015)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Load-bearingStrength:hedged· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one. The quote only partly states this claim.
- Not matched
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“It should also be noted that while everyday experience tells us that slower walking increases stability, we did not model or measure stability on rough terrain as a function of speed.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Voloshina and Ferris (2013) have shown that walking on uneven terrain causes only minor changes in stepping strategy and suggest that the changes in metabolic rate are instead due to a change in the amount of work carried out by lower-limb joints as well as changes in the timing of foot-ground collision and trailing leg push-off.”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
- Not matchedcites Voloshina and Ferris (2013)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:boosted· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
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A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Further, the preferred walking speeds of horses and elephants also are close to their minimum COT speeds (Hoyt and Taylor, 1981;Langman et al., 1995).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
Strength:plain· not yet calibratedCausal:correlational· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The Ben-Gurion University Human Subjects Research Committee approved the study and participants gave written informed consent.”
§ Preferred walking speed on rough terrain: is it all about energetics? > MATERIALS AND METHODS Subjects
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“Another sense that affects the human perception and selection of preferred walking speed is vision (Mohler et al., 2007).”
§ Preferred walking speed on rough terrain: is it all about energetics? > DISCUSSION
What the sources say
- Not checked — no full text of the sourcecites Mohler et al., 2007 source
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Thus, for the normalized data, although the fitted equations are not the same (Chow test), the normalized COT data for both surfaces show similar behavior as a function of normalized speed.”
§ Preferred walking speed on rough terrain: is it all about energetics? > COT change as a function of speed
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“We switched between X and Y (i.e. the fast speeds and the slow speeds) so that half the subjects performed the first sequence while the other half performed the second, to avoid trial order effects.”
§ Preferred walking speed on rough terrain: is it all about energetics? > Additional information
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
The paper relies on this without support.
These studies (on preferred speed and COT) were mostly performed on smooth, level ground or on treadmills.
“However, these studies were mostly performed on smooth, level ground or on treadmills.”
The authors state this as an assumption.
Rough terrain presumably introduces other factors, such as stability, to the objective function.
“Rough terrain presumably introduces other factors, such as stability, to the objective function.”
The paper relies on this without support.
To date, most research into walking and the COT phenomenon has been carried out on treadmills or smooth, level floors.
“To date, most research into walking and the COT phenomenon has been carried out on treadmills or smooth, level floors.”
The paper relies on this without support.
No one has examined COT as a function of speed on natural, rough terrain.
“However, to the best of our knowledge, no one has examined COT as a function of speed on natural, rough terrain.”
The paper relies on this without support.
Human walking efficiency primarily evolved on natural surfaces, not smooth floors or treadmills.
“First, human walking efficiency primarily evolved on natural surfaces, not smooth floors or treadmills.”
The paper relies on this without support.
Walking on rough terrain intrinsically requires the person to consider their stability while walking.
“Second, walking on rough terrain intrinsically requires the person to consider their stability while walking.”
The paper relies on this without support.
Slower walking on rough terrain increases stability.
“while everyday experience tells us that slower walking increases stability, we did not model or measure stability on rough terrain as a function of speed.”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The cited source says what the claim attributes to it.
In the citing paper
“Several recent studies of walking on rocky terrains found the individuals significantly reduced their step lengths to achieve more stable foot placement when compared with walking on flat, even surfaces (Gast, Kram, & Riemer, 2019; Matthis et al., 2018), which more than doubled their walking costs (Gast et al., 2019)”
From Forest terrains influence walking kinematics among indigenous Tsimane of the Bolivian Amazon (2022) · cites this paper as Gast et al., 2019
The cited source says what the claim attributes to it.
In the citing paper
“Cost differences could be closer to the range of the 50–115% increases previously measured for heavy brush and rocky terrains vs. even, hard surfaces (Soule & Goldman, 1972; Gast et al., 2019).”
From Forest terrains influence walking kinematics among indigenous Tsimane of the Bolivian Amazon (2022) · cites this paper as Gast et al., 2019
In the citing paper
“Reducing step length below that preferred on regular surfaces should increase the energy costs associated with walking on natural terrains like those in forests (Gast et al., 2019; Umberger & Martin, 2007)”
From Forest terrains influence walking kinematics among indigenous Tsimane of the Bolivian Amazon (2022) · cites this paper as Gast et al., 2019
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Conflicting standard deviations for optimal smooth-floor speed
MinorThe abstract reports a standard deviation of 0.03 m s−1, whereas the Results report 0.04 m s−1 for the same optimal speed. Table 1 gives 0.036 m s−1, which rounds to 0.04 at two decimal places.
“the speed that minimized COT (1.34±0.03m s -1 ).”
“The metabolically optimal average speed (the speed that minimizes the fitted COT functions) was 1.34±0.04m s -1 on the smooth floor and 1.13±0.07m s -1 on rough terrain.”
Conflicting average body masses
MinorThe subjects' average body mass is reported as 75.10 kg in Methods but as 76.5 kg in the appendix calculations.
“Ten healthy male subjects (body mass: 75.10±11.64kg, height: 1.82± 0.07 m, age: 27.5±1.6years; mean±1 s.d.) participated in this experiment.”
“where MR is the metabolic rate in watts, M is the body mass (for this study, the average body mass was 76.5 kg)”
Citations
Cites
Psychophysical bases of perceived exertion
BORG, G. A. V. (1982) · Medicine & Science in Sports & Exercise · doi:10.1249/00005768-198205000-00012 · Cited by 16,580
Multimodel Inference: Understanding AIC and BIC in Model Selection
Burnham, K. P., & Anderson, D. R. (2004) · Sociological Methods & Research · doi:10.1177/0049124104268644 · Cited by 11,648
Proceedings of the Human Factors and Ergonomics Society 2019 Annual Meeting
(2019) · Proceedings of the Human Factors and Ergonomics Society Annual Meeting · doi:10.1177/1071181319631171 · Cited by 1,438
Linear Mixed Models: A Practical Guide Using Statistical Software
West, B. T., Welch, K. B., & Gałecki, A. T. (2006) · Thammasat University Digital Collections · Cited by 1,382
Gait and the energetics of locomotion in horses
Hoyt, D. F., & Taylor, C. R. (1981) · Nature · doi:10.1038/292239a0 · Cited by 908
Energetic Consequences of Walking Like an Inverted Pendulum: Step-to-Step Transitions
Kuo, A. D., Donelan, J. M., & Ruina, A. (2005) · Exercise and Sport Sciences Reviews · doi:10.1097/00003677-200504000-00006 · Cited by 675
Derivation of formulae used to calculate energy expenditure in man.
Brockway, J. M. (1987) · PubMed · Cited by 567
Mechanical and metabolic determinants of the preferred step width in human walking
Maxwell Donelan, J., Kram, R., & Arthur D., K. (2001) · Proceedings of the Royal Society of London. Series B: Biological Sciences · doi:10.1098/rspb.2001.1761 · Cited by 552
Self-citationEffects of obesity and sex on the energetic cost and preferred speed of walking
Browning, R. C., Baker, E. A., Herron, J. A., & Kram, R. (2006) · Journal of Applied Physiology · doi:10.1152/japplphysiol.00767.2005 · Cited by 488
Self-citationWest, B. T., Welch, K. B., & Gałecki, A. T. (2014) · Chapman & Hall/CRC eBooks · doi:10.1201/b17198 · Cited by 485
Flagged first, then by citations
1 of the 46 references couldn’t be matched to a known paper.
Research works printed but not linked: 1
- Alexander, 2003, The best way to travel, 1
Cited by
Sorted by citations
Evacuation behaviors in tsunami drills
Chen, C., Mostafizi, A., Wang, H., Cox, D. T., & Cramer, L. A. (2022) · Natural Hazards · doi:10.1007/s11069-022-05208-y · Cited by 42
Walking is regulated by environmental temperature
Obuchi, S. P., Kawai, H., Garbalosa, J. C., Nishida, K., & Murakawa, K. (2021) · Scientific Reports · doi:10.1038/s41598-021-91633-1 · Cited by 34
Road Condition Detection and Emergency Rescue Recognition Using On-Board UAV in the Wildness
Liu, C., & Szirányi, T. (2022) · Remote Sensing · doi:10.3390/rs14174355 · Cited by 24
Behavioural energetics in human locomotion: how energy use influences how we move
McAllister, M. J., Chen, A., & Selinger, J. C. (2025) · Journal of Experimental Biology · doi:10.1242/jeb.248125 · Cited by 23
van Bijlert, P. A., van Soest, A. J. ‘., & Schulp, A. S. (2021) · Royal Society Open Science · doi:10.1098/rsos.201441 · Cited by 23
Metadata
- Authors
- Gast, K., Kram, R., & Riemer, R.
- Affiliations
- Ben-Gurion University of the Negev (IL)
- Department of Integrative Physiology, University of Colorado Boulder, USA
- Corresponding author
- Riemer, Raziel
- ORCID
- Riemer, Raziel
- Venue
- Journal of Experimental Biology
- Publisher
- The Company of Biologists
- Published
- 2019-01-01
- Volume
- 222
- Issue
- Pt 9
- ISSN
- 0022-0949 (ISSN-L)
- 1477-9145
- OpenAlex
- W2950067380
- Cited by
- 58
- References
- 46
- Citations by year
- 2026: 7 · 2025: 15 · 2024: 6 · 2023: 7 · 2022: 14 · 2021: 5 · 2020: 3 · 2019: 1
- FWCI
- 1.80
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Experimental Biology (publishedVersion)
- bioRxiv (Cold Spring Harbor Laboratory) (submittedVersion, cc-by)
- PubMed (publishedVersion)
- HighWire Press Open Archive (submittedVersion)
- Funders
- Leona M. and Harry B. Helmsley Charitable Trust and the Marcus Endowment Fund both at Ben-Gurion University of the Negev (through the Agricultural, Biological and Cognitive Robotics Initiative of Ben-Gurion University of the Negev.)
- Topics
- Physical Sciences › Engineering › Biomedical Engineering › Lower Extremity Biomechanics and Pathologies
- Health Sciences › Health Professions › Physical Therapy, Sports Therapy and Rehabilitation › Balance, Gait, and Falls Prevention
- Physical Sciences › Engineering › Control and Systems Engineering › Robotic Locomotion and Control
- Keywords
- preferred walking speed, uneven terrain, cost of transport, metabolic cost, energy cost of walking, gait stability, human locomotion
- MeSH terms
- Walking Speed, Adult, Energy Metabolism, Environment, Humans, Male
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-11-10, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-11-10 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Cited sources are checked with a language model’s help (gpt-6-sol).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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