The Perceived Point of Muscular Discomfort vs the Point of Failure in the Ageing Population- a Pilot Study

Overview

This is an investigation into the differences in muscle activation and numerical difference in reps between the feeling of moderate discomfort and technical failure during a set of bodyweight resistance exercise. The investigators know that resistance training is an essential tool for older people to maintain muscle function, valuable independence and autonomy in daily tasks. The idea of completing a set of resistance training activity to the point of failing a repetition due to fatigue regularly has been shown to not be appealing and could be a reason why there are low participation rates among older people for in weight training regularly. Research has also shown that it is not necessary to train to failure (being unable to continue to complete repetitions of an exercise with the proper technique due to fatigue), but the investigators would like to know if training to a point of moderate discomfort can also allow for the muscles to gain the positive changes associated with weight training, potentially making it more accessible and enjoyable. Using bodyweight exercises (a squat pattern and a push up pattern) the investigators will see how many repetitions after the point of perceived moderate discomfort is stated at which the point of failure is. the investigators will also measure muscle activation in the quadriceps and triceps with EMG (a device that can detect the muscles' electrical activity/ how hard it is working) to see at which point the muscle is working the hardest.

Before participation, the participant will undergo a health screening that follows the standard operating procedures of the Human Performance Laboratory. This involves measurements of height, weight, body fat percentage, blood glucose, blood pressure and heart rhythm abnormalities. Blood glucose will be measured using capillary blood via a finger prick test administered by the principal investigator. A very small amount of blood will be drawn into a capillary tube and then analysed in a machine (Biosen) to quantify the levels of blood glucose/sugar in the sample. Heart abnormalities will be measured using a device that is non-invasive and just requires the participant to place their fingers on a pad for one minute. The body fat percentage te69st is also non-invasive, requiring the participants to stand on a scale (Tanita body scanner) with their shoes and socks off. EMG electrodes will then be placed on the triceps and quadriceps after standard skin preparation has taken place. After this the participant will complete a standardised isometric maximal voluntary contraction so the EMG activity can be standardised as % maximal voluntary contraction (%MVC). The details of the MVC protocol can be found in Appendix 2. First the participant will be led through a standardized warm up that includes the use of elastic band exercises and joint mobility work for five minutes as seen in Appendix 3. The participant will be shown the technique of three variations of the two exercises using a mobile phone app video; beginner, intermediate and advanced variations. They will then be asked to choose which version of the exercise they think can achieve 8-15 repetitions with. All participants will then start with the beginner variation of the squat pattern exercise. If they are able to perform each exercise for more than 20 repetitions to technical failure they will be asked to perform the intermediate variation intermediate. If they are able to perform more than 20 repetitions to technical failure they will be asked to perform the advanced version. This process will then be repeated for the push-up pattern, of which there are also three variations, beginner, intermediate and advanced. To minimise fatigue between sets in those that are able to perform the intermediate or advanced exercises, lower and upper body exercises will be alternated and separated by 5 minutes of rest. Before each set they will be instructed to say the word "now" during the set when they begin to feel moderate muscle discomfort, (a 5 on a scale of 1-10), see appendix 3. (Fisher et al., 2017). and the scale is described to the participant as follows: "The scale begins at 0, which is described as no perceived discomfort. This can be likened to a perception of discomfort at a time where participant felt no noticeable sensations relating to physical activity. The scale ends at 10, which is described as the maximum perceivable discomfort. This can be likened to a perception of discomfort where the participant could not imagine the sensations relating to physical activity being any more intense." They will then be instructed to continue this set until they can no longer complete a repetition with the correct demonstrated form (technical failure). For each of the exercises the number of repetitions between the point of muscular discomfort and failure will be calculated and correlated with %MVC.