I recently read an article entitled ‘Beware the last rep’, the premise of which was that most lifting injuries happen on the last rep. I fundamentally disagree, and so does my esteemed friend Gary Bannister. Gary wrote the book on Arthur Jones’ work: ‘If You Like Exercise, Chances Are You’re Doing It Wrong’.
I asked Gary to comment on the premise of this article. Here’s his response (slightly edited) which I’m sure you’ll find enlightening.
“The suggestion that most injuries occur on the final repetition of exercise is totally misleading. Injury occurs when a system (in this case, the locomotive system –muscles, bones, ligaments, tendons and cartilage) is exposed to a force that exceeds its structural integrity. Said differently, its ability to withstand an overly-excessive force. For example, if the structural integrity of the muscles that support an elbow is 100 units, and the elbow is exposed to a force of 101 units, something breaks. Physiology suggests that the force produced by a working muscle is reduced throughout the performance of a set of exercise. The work of Nautilus® and MedX® inventor Arthur Jones determined that a muscle with an average mix of fibres lost approximately 2% strength per repetition during exercise. Which means that, following a set of ten repetitions, the average muscle loses approximately 20% of its initial strength - 20% of its ability to produce force. During the final repetitions of a challenging exercise, a muscle cannot produce enough force to hurt itself.
The greatest risk of injury exists during the first repetitions of an exercise, when a muscle is capable of producing its greatest contractile force; the least risk, during the final repetitions, when the muscle approaches a point of failure. It is exactly the opposite of how it feels. The first repetitions of a set of ten, for example, feel relatively easy, but are the most dangerous. The final repetitions of a similar set - when it feels like something is about to break - are actually the safest.
Two ingredients produce best results from progressive resistance exercise: intensity and good form. I believe that most injury during exercise is produced by ‘bad’ form – and form starts with speed of movement. If you suddenly ‘jerk’ the resistance during the first repetitions of an exercise, the working muscles are exposed to a force 3-5 times that of the selected weight. A 45kg weight, suddenly jerked, may expose working muscles to 135-225 kgs – stupid, when the tolerance of the involved structure is unknown. A similar ‘jerk’ during the final repetitions of exercise will elevate the forces involved to a lesser degree due to the muscle’s diminished ability to produce force (fatigue). Nonetheless, it should be avoided.”
In conclusion, the article suggests: “The more complicated the lift, the higher the risk of last-rep injuries since more muscles and body systems need to be engaged.” That’s exactly why I’m not a great advocate of complicated strength training exercise. It’s neither necessary, nor desirable, in terms of producing optimal results and minimising risk of injury.
So the take home message is twofold. Firstly, and Gary Bannister says it best: “Properly performed, high intensity exercise is not only the most efficient and effective method of training, it is also the safest.” And secondly, don’t assume everything you read and hear is the truth. In a world of uncensored fitness misinformation, it’s wise to be cautious. Rely instead on the sources you know you can trust, like BodyTech, where fitness integrity is paramount.