There is plenty of evidence when it comes to the effects of exercise/physical movement on health-related outcomes. For example, a recent metanalysis (compilation of high-quality research publications; Tarp et al., 2019) found that both cardiorespiratory fitness (CRF) and muscular strength can reduce the likelihood of Type 2 diabetes. Furthermore, Schmid and Leitzmann colleague’s (2015) metanalysis reported intermediate to a high level of CRF can reduce cancer-related mortality. Not surprising, that exercise has been shown to improve inflammatory markers and slow down the ageing process in humans by positively influencing skeletal muscle mitochondria (the powerhouse of the cell) and telomere (protect chromosome from damage) lengths.

In general, any form of exercise can help improve overall health, but many factors need to be considered for exercise to be effective long-term. So, the goal of this article is to make readers more informed about how anyone can take up exercise as long as they acknowledge and understand some crucial factors highlighted below.

Principle of adaptation

Biologically, right adaptation is key to the positive effects of exercise and physical activity and our bodies tend to adapt to a new stimulus over some time. If the stress (stimulus) is too much too soon then the adaptation process may be impaired hence chances of injuries and or disease is higher. For example, rhabdomyolysis (breakdown of muscle tissue that releases a damaging protein into the blood) seen in people who exercise too hard too soon and often. On the opposite end of the spectrum, if the stimulus is too low then the adaptation will not be adequate to provide any meaningful changes physiologically. Therefore, the right amount of stress with adequate rest is crucial for a positive change in physiological markers that can improve health-related outcomes.

Relationship between intensity and volume

The relationship between intensity and volume is inverse, which means as the intensity of an exercise increases, we are less likely to sustain it for a longer duration. This is primarily because energy demands for a high-intensity exercise/activity are different to that of a lower-intensity exercise/activity. The higher the intensity of an exercise, limited oxygen is available (often termed as anaerobic) and more energy is required hence it is difficult to sustain for a long duration. If the intensity of an exercise is low, then the same activity can be sustained for a longer duration. For example, walking five kilometres compared to sprinting 100m. Due to the popularity of high-intensity interval training (aka HIIT), many people think that they are performing high-intensity exercises regularly (more than three times a week) but a true high-intensity interval training is difficult to perform frequently as it requires enough recovery time due to the energy expenditure.

High-intensity interval training gained popularity from a study by Tabata and colleagues (1996) that reported participants who performed high-intensity exercises (170 per cent VO2 max-maximal oxygen uptake) for 20s with 10s rest, seven-eight sets for five days a week improved aerobic and anaerobic capacity compared to participants that performed moderate-intensity exercises. However, the study had very low participants (n=7) and 170 per cent VO2 max is realistically not possible for most people with a recovery of 10s. It is important to put context to research before we standardise and apply it across a big cohort of people.

To repeatedly perform high-intensity exercises is even harder as we age, although high-intensity exercises can be useful to improve physiological markers, they should be context-driven and person-specific. A simple and practical approach to alter intensity in training could be maximum aerobic speed (MAS). This can be done by simply dividing a set distance by time taken to complete the distance.

For example, if you run 1.5 km in five minutes then the MAS is 18kmph (1,500 m/300s), now if you want to plan a low-intensity training day then you can reduce the speed and increase the distance whereas if you want to perform high-intensity interval training then you can break the entire 1,500m in bouts of 100-300m and perform them at above 18km/hr intensity with adequate recovery between bouts. This is much more realistic and can be applied across activities such as walking, swimming, bike, rowing. For beginners, the key is to start with the minimum effective dose, that is, minimal volume and intensity that can elicit positive physiological change.

Variation in joint structure

When we perform exercises/ activities, it is also important to acknowledge variations in the structure of the joints. For example, due to the structure and design of the lower back (lumbar spine), it is not capable of excessive rotational forces whereas the hips and upper/mid-back (thoracic) are capable of far more rotation (> 2 times) due to their structure. Therefore, when we engage in an activity such as golf it is important to utilise the rotational capability of the hips and upper/mid back as opposed to relying excessively on the lower back. Additionally, the structure of the joints can vary between people.

For example, due to the structure of the hip joint (neck of femur) in relation to the pelvis (acetabulum), not every person will be able to deep squat. One easy way to assess if there is a structural concern with any movement is when we feel bone on bone as we move into the end range. Therefore, forcing excessive range of motion in these situations may cause injuries and hinder long-term participation. Rather focusing on alternative exercise (that serve the same purpose) or modifying the exercise can be much more beneficial in the long run.

Dr Kaushik Talukdar is the founder of Athlete Institute (https://athlete.institute) and you can email him at kaushik@athlete.institute or tweet @coachkaushik