Blog by Dr. John Cronin

Do you want stronger and longer hamstrings that super boost your speed and reduce injury risk to boot? Here is a 2 + 2 for you.

I get 4 – see if you do.


Sprint Training Vs Nordic Hamstring Eccentric Training

  1. A big thanks to Luke Nelson putting me onto Jurdan Mendiguchia’s latest research where the group compared the effects of Nordic hamstring eccentric (NHE) strength training to sprint training as part of a regular soccer practice. The variables of interest were sprint performance and mechanics as measured by radar, and biceps femoris architecture as measured by ultrasound. Interestingly they found that sprint training was superior to NHE strength training in increasing biceps femoris long head fascicle length and muscle thickness, as well as improving sprint performance.  They concluded that only sprint training was able to both provide a preventive stimulus (increase fascicle length) and at the same time improve both sprint performance and mechanics.


Thigh and calf loading on Sprint Mechanics

+2. Just out of Swansea University from the lab of Neil Bezodis was a study by Hurst et al. (2020) that investigated the effects of unloaded vs thigh and calf wearable resistance loading during maximum velocity sprinting. They measured a lot of variables, however staying focused, one finding of particular interest to this article was that shank/calf loading led to a small increase in peak biceps femoris muscle-tendon length.

In Combination

  1. Now here is the reach but intuitively it makes sense to me. Sprint train with wearable resistance attached to the calf. The likely benefits given the above research are: 1) increased fascicle length changes of the biceps femoris at least; 2) because of the added resistance you will be stronger at these longer lengths; 3) because of the high velocity strength training, tissues will be more injury resistance at high velocities; and, 4) I bet you run faster as well.  What do you think?



We know the NHE trains the hamstrings in a very limited range of motion and is less likely to strengthen the hamstrings at longer lengths, which is however where most hamstring injuries occur. Furthermore, research has shown that approximately 80% of hamstring injuries involve the BF long head yet, researchers have shown that the NHE preferentially targets the BF short head and the semitendinosus. So, what say we incorporated a couple of wearable resistance loaded exercises in these sprint sessions that purposely targeted the length and strength of the hamstrings, the straight leg shuffle and B-skips come to mind?  I am thinking a lot of positive adaptation to architecture and sprint performance.  These are some thoughts rumbling around my head but as Steve McCaig said to me, “it’s easier to ask them than answer them.”




Hurst, O. et al.   (2020).  Acute effects of wearable thigh and shank loading on spatiotemporal and kinematic variables during maximum velocity sprinting, Sports Biomechanics,

Mendiguchia et al. (2020) Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players. PLoS ONE 15(2): e0228283.



Dr. John Cronin is recognised internationally as one of the world’s leading sports scientists. He is a Professor of Strength and Conditioning at Auckland University of Technology’s Sports Performance Research Institute New Zealand. As our Head of Research, Dr. Cronin oversees all EXOGEN® wearable resistance research globally.

The Sports Performance Research Institute New Zealand (SPRINZ) is New Zealand’s number one rated sports research institute with a growing global reputation. SPRINZ is a group of dynamic and innovative researchers producing applied research in improving human health, sports performance and long-term athletic development.