Essential Training Principles

Updated: Jul 11, 2021

Every training session should include four phases: 1) warm-up; 2) main session; 3) cool-down and 4) stretch. In this article you will discover why and how.

a fit woman preparing to engage in physical exercise. She is about to warm up before a 10 minute HIIT session.

To get the most out of training we should ensure that each exercise session transitions through four distinct phases: 1) Warm-up; 2) Main Session; 3) Cool-down; and 4) Stretch.

By observing this time-honoured training principles we will not only improve physical performance but also reduce our chances of falling foul to injury during exercise.

Studies abound demonstrating a strong link between warming up and reduced injury susceptibility (see below).

Moreover, concluding a training session with a cool-down and stretch will likely reduce the severity of the DOMS (delayed onset of muscle soreness) whilst also speeding post-exercise recover.

Yet, even though these positive outcomes of correct training are well understood, which accounts for why professional athletes and sports coaches faithfully observe them, few people who regularly participate in exercise do.

The aim of this article is to provide the reader with an insight into the benefits of each phase as well as ideas of how to approach them.


Phase 1: The Warm-up

A fitness class warming up prior to taking part in a circuit. The training session they are going to complete is a whole-body high intensity workout.

Conventional wisdom maintains that preliminary exercise helps the performer prepare either physiologically or psychologically and reduce the likelihood of joint and muscle injury.

McArdle, Katch & Katch

The warm-up is a crucial part of physical training and it ought never to be neglected. Prior to engaging in exercise (or sport) it is prudent to participate in a 10- to 15-minute whole-body warm-up.

Why? You may well ask.

An appropriate warm-up not only enhances physical performance but also prepares the body for exercise by bringing about a number of important physiological changes. These changes include raising core and muscle temperature, facilitating neuromuscular function and preparing the trainer psychologically (Watson 1995).

But the most important change here is the rise in muscle temperature. When muscles are warmer, they become more flexible, supple and less susceptible to injury. It is for this reason and those previously mentioned why you must – at a MINIMUM – spend ten minutes warming up prior to engaging in exercise.

Benefits of warming up include

1: Increase in joint mobility
2: Increase in blood flow throughout the body
3: Increase in aerobic metabolism
4: Decrease in lactic acid production
5: Increases maximum power output
6: Orientates the trainer’s psychology to exercise

(List adapted from Watson’s Physical Fitness & Athletic Performance – pp. 79/80)

Best types of warm-up activities

Rowing: because it activates the two major muscle groups
Cross-trainer: much for the same reason as the rower
Rowing interspersed with body weight and light resistance exercises

How to warm-up properly

The example below was designed as a warm-up to be completed prior to a run. Although it has been designed specifically for running, the same underlying principles can be applied to circuits, cycling, rowing and general gym sessions – in short, any form of physical exercise.

10-minute progressive warm-up

  • Walk for 2 minutes

  • Break into a slow jog

  • Jog for 3 minutes

  • Stop and complete 10 squats, 10 burpees and 10 squat thrusts (30(ish) seconds)

  • Carry on jogging for a further 2 minutes but increase tempo

  • Stop and complete 20 squats, 20 burpees and 20 squat thrusts (1(ish) minute)

  • Carry on jogging for the remaining time and progressively build the pace up to what the run will be at – this warm-up will integrate into the main session, which is what a good warm-up should do

This is a very simple progressive warm-up. Yet it would more than suffice to prepare the body for exercise. Of course, I am not suggesting that the exact exercises above be used, just the method: gradually building up the intensity; ensuring that the exercises within the warm-up reflect that of the main session.

In the exercise profession there are opposing schools of thought regarding whether stretching should be included within the warm-up. Some argue that stretching should be included and others that it shouldn’t.

I personally subscribe to the shouldn’t camp. My reason: stretching, more specifically ‘static stretching’, is, essentially, a relaxation technique. Inducing a state of relaxation prior to participating in rigorous physical exercise is going to be counterproductive and thus negatively impact performance. Furthermore, because static stretching is, by definition, static, any rise in core temperature previously generated will be lost.

A gradual warm-up, like the example above, that builds in intensity over 10 to 15-minutes, will prepare you both physically and mentally for the coming session.

Warm-up summary

  • Ensure that the muscles which are going to be worked in the main session are focused on during the warm-up. Basically, I am trying to say it would be borderline useless cycling for 10 minutes when your main session consists of an upper-body weights circuit. A warm-up should consist of a cardiovascular element, but what an experienced trainer would do is supplement the cardio exercise with ones that are going to be used within the main session.

  • Start off slow and GRADUALLY, over the 10/15 minutes, increase the intensity.

  • Include a cardiovascular exercise such as running, cycling rowing, etc. to your warm-up as this will raise the body’s core temperature.

  • Spend no less than 10 minutes warming the body up.

  • There is absolutely no need to stretch prior to physical exercise – I am not taking martial artists, gymnastics (or other similar disciplines and sports that require an increase in muscle flexibility) into consideration with this statement. I am only referring to exercising, as in the pursuit of improving physical performance.


Phase 2: The Main Session

a group of people exercising in a circuit

The main part of the training session is where we get fit! For however much time you have budgeted, and a main session can last for as little as 20-minutes or as long as an hour, you will focus on a specific aspect of your physicality – strength, muscular endurance, cardiovascular – or engage in a whole-body circuit.

The type of training that you participate in is entirely predicated on your fitness goals and physical aspirations. For example, if you aspired to develop functional strength, then your session might feature CrossFit-style exercises. But if your fitness concern centred more around health, as opposed to, say, developing a specific component of fitness, then you might conduct a circuit or a HIIT session.

Though it could be argued that there is no best way to train, and that the style of training that a person participates in is (should be) predetermined by their goals, few would refute the contention that not all methods of training were created equally. And by that I mean, some methods of training are far more effective at delivering certain results than other methods.

A person who harboured the fitness goal of improved health would be wasting their time by engaging solely in static resistance exercises. For such exercises will not adequately stimulate their cardio-respiratory system. Thus, those physiological responses and adaptations synonymous with health – that is, the metabolisation of superfluous non-force producing tissue (aka fat!) and the improved efficiency of the heart and lungs – will not take place.

Main session summary

  • There is no minimum or maximum duration a main session can or should last for. However, between 30 to 60-minutes is considered optimal.

  • The method of training is determined by your fitness goals.

  • If you are not pursuing a specific fitness goal but are engaging in exercise for the associative health benefits, it is recommended that your main sessions include a mix of cardio and circuits.


Phase 3: The Cool-down

a person conducting a post-training cool-down on battling ropes

After you have conducted a training session, irrespective of what you did and the intensity your exercised at, it is good practice to conclude with a cool-down. By implementing this sage advice, you could be reducing the severity of the DOMS whilst aiding the repair and recovery of damaged tissue – the inevitable consequence of exercise.

Additionally, the cool-down provides us with time to devote to the development of exercise technique. For example, when after a tough circuit or HIIT session, I typically spend 5 to 10 minutes cooling down on the rower. But instead of mindlessly moving backwards and forwards, I work on my technique. This approach – the one of using the cool-down to improve technique – could be applied to resistance exercises; however, the weights would be very low.

Remember: the cool-down should be completed a low intensity.

So what constitutes as an effective cool-down? A cool-down can consist of something as simple as rowing a couple of thousand metres. Merely pop on the rowing machine (or cross-trainer or treadmill) and proceed to deescalate your physiological systems.

Other effective methods include retracing your steps, in a relaxed manner, back through part of the main session or repeating the warm-up in reverse.

Cool-down summary

  • Begin the cool down at an intensity that is considerably lower than that of the main session.

  • Gradually decrease the level of intensity over a 5 to 10-minute period.

  • At the end of a cool down all exercising – whether it may be rowing, cycling, swimming, running or carrying on with the circuit – should resemble the same level of intensity as slow walking.

  • When you are feeling relaxed and you have somewhat recovered from the main session, this then signifies the time to begin the stretch.


Phase 4: The Stretch

a woman completing a stretch after exercise

According to the American College of Sports Medicine a mere ten minutes of daily stretching can reduce your chances of incurring an exercise-related injury by as much as 50%* - which is a whopping pay-off.

In the literature there is a ton of research that supports the relationship between improved flexibility and reduced injury. For example, one study conducted on 200 college athletes ‘found that the risk of injury decreased as flexibility improved,’ (Norris 2004). Moreover, the researchers showed that those athletes who did not develop their flexibility suffered 15% more injuries.

Other benefits of stretching

Most importantly: regular stretching can reduce injury risk
A consistent stretching regime may, over time, improve your body alignment and posture
Reduces the severity of the DOMS (delayed onset of muscles soreness)
Improves body control and awareness
Greater increase in movement around the joint (ROM)
Stretching, simply put, makes you feel good

It’s for these reasons why we should endeavour to include at least 10-minutes of stretching into our day – and, at the very least, certainly after we have exercised. To facilitate the implementation of this positive intervention, that of engaging in 10-minutes of daily stretching, I have put together a basic stretching guide for you.

Stretching Guide

Though stretching (flexibility) is a crucial and extremely important component of fitness it is probably the one that is most overlooked. Why this is the case I couldn’t quite say; maybe the vast majority of trainers are incredulous to the benefits of stretching.

Whatever the reason ensure that you are not among these risk takers and implement a stretching regime. It’s easy to do and for the little time it takes the rewards could be substantial.

The accompanying guide, if followed, will ensure that you engage in a 10-minute whole-body stretch. Once you have familiarised yourself with the seven stretches that feature in the guide, you might want to include your own or reshape the guide so that it targets specific muscle groups.

Stretching Guide - How 2
Download DOCX • 941KB

Methods of stretching

The types of stretching we can do to improve our flexibility include static or developmental stretches where we hold the position for between 20 seconds and 1 minute. When working through a stretching regime, and this is best done post exercise, it is advisable to include the major muscle groups whilst also paying additional attention to those muscles predominantly worked during the session. So even if your main session consisted of, say, a five-mile run, you should still stretch the muscles of the upper body but ensure to focus extra time on the quads, hammys and calves.

Below I have outlined two strategies that you could implement to ensure that you get at least 10-minutes of stretching into day.

Strategy 1: Probably one of the best ways to ensure that you get your 10 a day is by bolting a stretch on to the end of you training/sports sessions. As soon as you finish pumping iron or pounding the tarmac immediately (or after the cool-down) initiate your stretching regime. Begin with the muscles of the upper body and slowly work down to those of the legs.

The ACSM recommends holding each stretch for 10 to 30 seconds each. However, I read a report recently that suggested holding post-exercise stretches for between 20 seconds to 1 minute and repeating each stretch 2 to 3 times. Basically, you perform stretches as you would a resistance exercise, the only difference being the reps are replaced by time and the intensity is much lower.

A stretch should never cause physical pain or discomfort. It should induce a mild sensation in the area being stretched.

Strategy 2: Another method you can use to get more elasticated is by introducing into your life the Yogic science. This is my secret weapon against injury. Every morning, without fail, I scrape myself out of bed about 5ish, roll out the Yoga mat, and slowly work through a series of sun salutations and various floor exercises.

I’ve been doing this religiously for about a year now and not only is it a beautiful way too start each day but it has noticeably increased my flexibility which has translated into fewer injuries and improved physical performance. I cannot sing more highly the praises of Yoga.

Try this challenge: 30 Days of Yoga

Session Plan

Below you will find a generic outline – or template – of an exercise session. Each of the four phases includes suggested times and range of possible exercises. Of course, you don’t have to implement it verbatim. The session plan is merely supposed to act as a guide. What is important is that every training session that you take part in follows the prescriptive format and that each of the four phases is clearly distinguishable.

1: Warm-up (10 to 15 minutes)

2000m row (or 10-minutes cross trainer)

1 up to 5 press-ups

1 up to 5 burpees

1 up to 5 hanging leg raises

2: Main session (40-minutes)

Try this 1000rep circuit

3: Cool-down (5 to 10-minutes)

1000m row at a medium intensity

1000m row slow, focusing on technique

4: Stretch (5 to 10-minutes)

See Stretching Guide


(As we are very interested in user experience here at Hungry4Fitness, we would be very grateful if you could take a few seconds out of your day to leave a comment. Thanks in advance!)

Blog Author

Adam Priest, former Royal Marines Commando, is a personal trainer, lecturer, boxing and Thai boxing enthusiast.



McArdle, W. D., Katch, F. I., Katch, V. L (2001) Exercise Physiology Fifth Edition. Lippincott, Williams & Wilkins

Norris. M. C (2004) Stretching. A & C Black. London.

Watson A. W. S (1995) Physical Fitness & Athletic Performance. Longman. England.

*Unfortunately I was unable to locate the citation for the ACSM statistic.

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