Running Up That Hill
by Doug Stewart
No, I am not late to jump on the Kate Bush bandwagon… but referring to a new piece of research assessing vertical loading rate when running on an incline at different slopes and speeds. However, that was significantly less snappy than Kate’s song title!
The new research, entitled ‘Correspondence Between Values of Vertical Loading Rate and Oxygen During Inclined Running’, took 10 female and 19 male runners (average age of 34 years and VO2Max of 56.5) and had them do 4-minute run tests on a treadmill at varying slopes. The participants ran in a randomised order at -20%, -10%, -5%, 0%, +5%, +10%, +15% and +20% and at 8, 10, 12 or 14kph. They completed 3 sessions, with 1 week rest between each, and did 7 to 8 of the 4-minute runs at varying speeds/slopes each session (with rests between each to ensure recovered). Various control measures were also gathered as a baseline.
Vertical Loading Rate (VLR) is used as an indicator to describe ground contact, and is the rate of change in the force applied after the foot hits the ground. VLR is higher when running downhill (larger impact with the ground) compared to level running and running uphill if running at the same speed.
The authors discovered that VLR reduced by 27% on the +5% slope and by 54% on the 10% slope, compared to flat running, at a similar respective intensity for the runners. Moreover, if running at maximum aerobic intensity, the researchers predict that VLR would drop by 52.7% at +5%, 63% at +10% and 73.3% at 15% slopes.
With respect to downhill slopes, these generated high VLR but, unlike flat and uphill running, there was no correspondence between the speed and VO2.
Therefore, the researchers conclude that uphill running can be used as a way to minimise ground contact forces due to the lower VLR, whilst being able to increase energy expenditure in a shorter duration compared to level running. This means that uphill running can minimise the mechanical loading on the body, whilst achieving the same energy expenditure (calories burned) in a short timeframe. This may serve as an opportunity for those returning from injury and wishing to minimise ground impact and/or duration of training sessions.
There may also be an alternative goal of training, where one is looking to increase VLR, to generate significant mechanical and or/neuromuscular adaptations. In this scenario, downhill running presents a greater opportunity compared to flat or uphill running in athletes who are uninjured and looking in increase ground contact forces.
References:
Lemire, M., Falbriard, M., Aminian, K. et al. Correspondence Between Values of Vertical Loading Rate and Oxygen Consumption During Inclined Running. Sports Med - Open 8, 114 (2022). https://doi.org/10.1186/s40798-022-00491-2