At Complete Physio Richmond, we collaborate with our friends at The Richmond Gym, sharing expertise to help our community achieve their health and fitness goals. After highlighting 4 key exercise principles last month, Founder James Ross discusses the concept of “No Pain, No Gain” and breaks down what soreness really means in relation to your training outcomes.
Together with James, we will be launching a new Strength and Conditioning workshop for Allied Health Professionals in 2025 – if you want to be waitlisted for this great PD opportunity, please email us.
No pain no gain is a mantra that is often bandied around when it comes to physical culture. This has led to some people only taking satisfaction in a training session if their muscles are sore afterwards. This blog will build on the ‘slow and steady wins the race’ article and offer more detail about pain during and after a session.

The main take home from this blog is that during hard training some discomfort is common. However, you should use your past experience as a bit of a guide. After training you may get some soreness, but this does not necessarily mean that you’ll get better results. Therefore, there’s no need to chase soreness.
Soreness and lactic acid
During intense training, we can often feel a burning or heaviness within the muscle. This burning sensation is often blamed on the dreaded ‘lactic acid’. However, despite its reputation, it is not to be blamed for this painful sensation. During intense exercise when the aerobic system cannot meet the metabolic demands, the body calls upon anaerobic energy systems that function without needing oxygen. This causes ‘lactic acid’ production which is quickly buffered to lactate, there is a very tight correlation with hydrogen ion production. It is these hydrogen ions that cause this acute discomfort. However, initially when blood lactate was measured it was very well correlated with this painful sensation giving rise to its demonization.
When may this discomfort be appropriate during training?
- Resistance training with light weights for high repetitions to failure
- Performing intense interval training sessions
Soreness during resistance training
To stimulate muscle growth with light weights, sets are often performed to failure. By performing a set to failure you ensure that all the fibres have been stimulated – as the set progresses there will be an increasing sense of discomfort eventually resulting in your inability to perform another repetition. When using a sub-maximal load you do not stimulate all the fibers concurrently like you do with heavy weights. The recruitment of muscles (motor units) follows what’s referred to as the size principle which means that the smaller slow-twitch muscle fibres are recruited first and as they fatigue the larger, fast-twitch fibres are recruited.
In this context, some degree of discomfort is to be expected when you’re training intending to achieve failure. When the muscle is contracting hard it is difficult for the blood to penetrate or perfuse into the muscle to deliver oxygen. This limits the muscles ability to work aerobically so some degree of discomfort may be expected, but by no means is a must.
If you wanted to avoid ‘the burn’ training with heavier loads may not require you to go to failure to stimulate muscle growth. This is because the higher effort to perform each repetition may simultaneously recruit the fast and slow twitch muscle fibres. So overall, your training methodology may determine the amount of acute discomfort you may expect during a resistance training session.
Soreness during endurance training
Intense endurance training may also cause discomfort within the working muscle. Training at higher intensities is one of the best ways to improve your VO2 max, during these efforts, the anaerobic system will also get recruited so some degree of discomfort may be expected. Typically spending five to ten minutes above 90% of your maximum heart rate is considered optimal for improving VO2 max, however, these high-intensity efforts may be hard to maintain.
Managing and understanding soreness related to training
Discomfort during intense training is useful feedback to help you pace your effort in accordance with your body’s abilities. However, it’s worth pointing out that if you experience something different from what you traditionally do, you may need to address it. So the best way to manage this is to train in a way that you’re accustomed to, but slowly pushing your boundaries as opposed to dramatically pushing them like you’ve just read David Goggins latest book! By making slow, incremental improvements you will have context for the sensations you’re feeling in your body allowing you to discern what is helpful and what needs to be addressed.
Some acute pain triggered by changes in your metabolism may be experienced during the session if you are training with high reps to failure or with high intensity during your endurance training. However, soreness after the session is typically triggered by the immune system.
Muscle soreness a day or two after training is called delayed onset muscle soreness (DOMS). DOMS is typically associated with microtrauma to the muscle. Microtrauma may help signal for the muscle to adapt by growing bigger.
Soreness, muscle growth and progressive overload
Therefore, the more soreness after a session we have the more muscle growth we get?
This sounds logical, however, there isn’t a good relationship between muscle damage and DOMS! When we perform a novel training session that has a lowering contraction or eccentric muscle action we get a protective effect for our next session, which is called the repeated bout effect.
Further, muscle growth is the net accrual of muscle mass so if you break down too much muscle your body has to get back to baseline before causing a net gain in muscle mass. So we want to find the Goldilocks zone where the dose allows us to recover sufficiently.
A simple solution is using small incremental changes, which allows us to follow the principle of progressive overload. The benefit of repeated bouts is that they reduce soreness and challenge your body enough to create a stimulus. To summarize, whether you’re introducing different resistance training exercises or increasing your sprinting intensity, slow incremental changes will be beneficial.