Energetics and muscle-tendon function in gait Neil J. Cronin - - PowerPoint PPT Presentation

Energetics and muscle-tendon function in gait

Neil J. Cronin

Neuromuscular Research Centre, University of Jyväskylä, Finland

• 1. Humans are excellent walkers

Humans ‘choose’ economical speed / SR

Bramble & Lieberman, 2004 Nature Umberger & Martin, 2007 JEB

Human walking is comparatively economical

McNeill Alexander, 2005 JEB

Human walking is mechanically economical

Lichtwark & Wilson, 2006 JEB

Minimal muscle work Elastic tendon

Roberts & Azizi, 2011 JEB

→ → 4 months ‘rest’ → “His bpm…he monitor”.

7 marathons, 7 days, 7 continents (at the age of 59)

• 2. Humans are excellent runners

Snyder & Farley, 2011 JEB

Humans also ‘choose’ the optimal running SR

Normalised stride rate (% preferred) Normalised metabolic cost (% cost at preferred)

Bramble & Lieberman, 2004 Nature

Human running is metabolically economical

Human running is comparatively economical

Rubenson et al., 2007 JEB

Human running is mechanically economical

Lichtwark et al., 2007 J Biomech

Muscle Tendon 1 Running stride

Farris & Sawicki, 2012 Proc Natl Acad

Gastrocnemius Shortening velocity

2.7 km/h 7.2 km/h

Muscle force

4.5 km/h 6.3 km/h

Human running is mechanically economical

Lichtwark et al., 2007 J Biomech

Muscle Tendon 1 Running stride

Farris & Sawicki, 2012 Proc Natl Acad

Gastrocnemius Shortening velocity

2.7 km/h 7.2 km/h

Muscle force

4.5 km/h 6.3 km/h 7.2 km/h

• 3. Humans are terrible race walkers

America’s

Bramble & Lieberman, 2004 Nature

’Normal’ walking speed Race walking speed

Race walking: A human invention

Race walking is metabolically costly

100 120 140 160 180 200 220 240 260 280 300 5 10 15 20 25

Data from 4 olympic race walkers

Walking Running Race walking COT (ml O2 / kg / km) Speed (km/h)

Menier & Pugh, 1968 J Physiol

Race walking is energetically costly

Cronin et al., 2016 JAP.

• 4
• 2

2

MG

10 20 30 40 50 60 70 80 90 100

• 4
• 2

2

Soleus Stride cycle (%)

10 km/h Racewalk Fast Racewalk 10 km/h Run Fast Run

Race walking is mechanically costly

Fascicle velocity MTU length

Run Race walk

Cronin et al., 2016 JAP.

Tak ake e ho home me me messages sages

• 1. We are economical walkers and can cover

extremely long distances at relatively low cost.

• 2. We are economical runners, even compared to
• ther species.
• 3. Humans did not evolve to race walk. Even after

decades of training, race walking is uneconomical.

neil.j.cronin@jyu.fi