Observations on Treadmill Training

Every time I visit the gym, I can’t resist myself from running on the treadmill. I would work on overall body strengthening exercises combined with core strengthening followed by a fast 5k run. Primarily I make use of the treadmill for correcting my posture and improving the lactate threshold. Usually it takes 21:30 – 21:50mins for me to complete a 5k on a treadmill with an average speed of around 13.9km/hr. Whether its road running or treadmill running I have the style of taking longer strides. The distance on the treadmill is calculated only based on the time and speed but not on the stride length and rates. If my strides are longer, definitely I would be covering more than 5k on the treadmill in sub 22 mins. Recently with less intensity I broke my 5k PR on road in 21:51 mins which again contradicts with the treadmill timing. After doing some research on stride length and speed, I came across a good article on Treadmill Training.

Few interesting points from the article

The first study to evaluate carefully the kinematics of treadmill versus 'overground' running was completed in 1972 at Penn State University in the US, in a study of 16 male members of the university's track and cross-country teams(4). The runners were evenly divided between distance specialties, with five sprinters, six middle-distance runners and five cross-country runners, all of them required to run at three speeds at three different inclinations on both the treadmill and normal ground.

This groundbreaking study uncovered fundamental differences between treadmill and overground running. For instance, at relatively routine speeds of 3.35 and 4.88m/sec (119 and 82 seconds per 400m respectively), the athletes' stride lengths were absolutely identical on treadmill and firm ground; but when velocity rose to 6.4m/sec (62.5 seconds per 400m), treadmill stride length was about 5% longer than overground strides. The same situation occurred during uphill (10%-grade) running, with strides equal at moderate paces but about 8% longer on the treadmill when velocity rose to 6.4m/sec. During downhill running (10%), stride lengths on the ground and treadmill were equal at all speeds.

Not surprisingly, stride rates were lower on the treadmill during fast running both uphill and on the level: since stride lengths were longer on the treadmill, stride rate would have to slow down in order to keep speed at a constant level. Predictably too, 'support time' (the length in milliseconds of the stance phase of the gait cycle) increased significantly on the treadmill for all speeds during uphill and downhill running - and at the very highest speed during level running. Basically, the runners were trying to create more stability for themselves on the unstable, fast-moving and/or inclined treadmill by keeping their feet on the belt a little longer than usual. In fact, this effect may have been the cause of both the lower stride rates and longer strides: with the stance phase elongated, more propulsive force could have been created, broadening strides but trimming stride rate.

No wonder my stride length was longer on the treadmill at higher velocity.