The Effects of Exercise on the Body

This is a video from the Level 2/3 Diploma in Personal Training from www.fasterfunction.com written by me, for students going through my course.

I won’t share all of the videos from the course, but I will share ones that give you an idea of what a Personal Trainer needs to learn to qualify.

The reason I like to share the lecture is because I get to tell you in my own words about some of the information we have to teach, that might not be as correct or relevant as it is made out to be (cough, cough, blood pooling).

I hope you enjoy my performance of DOMS!

In this section of the course, you will learn the following

1.1 Describe cardiovascular and respiratory adaptations to endurance/aerobic training

1.2 Identify the short- and long-term effects of exercise on blood pressure

1.3 Describe the “blood pooling” effect following exercise

1.4 Describe the effects of exercise on bones and joints including the significance of weight bearing exercise

1.5 Describe delayed onset of muscle soreness (DOMS)

1.6 Identify exercises or techniques likely to cause delayed onset of muscle soreness

1.7 Describe the Valsalva effect and where it may be advantageous and contraindicated

1.8 Describe the short- and long-term effects of different types of exercise on muscle

1.9 Describe different exercises that can improve posture

Introduction

In this module, you will start to learn about the effects of training on the body. We will take you through the short and long-term effects of exercise on the body, so that when you get to train a client, you will be able to easily help them understand what they are feeling in the short term, how they should expect to change and how to keep them safe.

1.1 Describe cardiovascular and respiratory adaptations to endurance/aerobic training

Many people, when they think of exercise, think of running, swimming, cycling, aerobics classes, or cross-country, if this is the first time they've tried exercise since school. Our first look at exercise is the endurance / aerobic training exercises that we would give a client.

Endurance or aerobic training places sustained demand on the heart and lungs, prompting a series of physiological adaptations that enhance oxygen delivery and utilisation.

Over time, regular aerobic exercise, such as long-distance running, cycling, or swimming, leads to both structural and functional changes in the cardiovascular and respiratory systems.

These changes not only improve performance but also offer health benefits such as reduced risk of heart disease.

• Increased stroke volume and cardiac output

  • The left ventricle enlarges (eccentric hypertrophy), allowing it to fill with and eject more blood per beat (Mitchell et al., 2013¹).

  • At rest and during submaximal exercise, heart rate decreases for the same workload, reflecting improved efficiency.

• Lower resting and submaximal blood pressure

  • Regular training reduces arterial stiffness, improving compliance and lowering systolic pressure over time (Cornelissen & Smart, 2013²).

• Enhanced capillarisation of muscle tissue

  • New capillary networks form around muscle fibres, shortening diffusion distance for oxygen and metabolites, which improves endurance capacity (Prior et al., 2004³).

• Improved respiratory muscle strength and endurance

  • Diaphragm and intercostal muscles become stronger, reducing the sensation of breathlessness during high‐intensity efforts (Rodriguez et al., 2012⁴).

• Increased maximal oxygen uptake (VO₂max)

  • VO₂max can rise by 15–20% in previously untrained individuals, reflecting improved oxygen transport and utilisation (Jones & Carter, 2000⁵).

Example: A client preparing for a half‐marathon might start with 20 minutes of steady‐state running at 60% of their maximum heart rate. Over 12 weeks, their resting heart rate may drop by 10 beats per minute and their 10 km time improve by 5–10%.

1.2 Identify the short- and long-term effects of exercise on blood pressure

Exercise has both immediate (acute) and cumulative (chronic) effects on arterial blood pressure. Understanding these can guide safe prescription, especially in clients with hypertension or cardiovascular risks.

• Short-term (acute) effects

  • Systolic blood pressure (SBP) rises during exercise due to increased cardiac output.

  • Diastolic blood pressure (DBP) may stay the same or change minimally because of vasodilation in working muscles.

  • Post-exercise hypotension: SBP and DBP can fall below pre-exercise levels for up to 12 hours after moderate‐intensity activity (Pescatello et al., 2004⁶).

• Long-term (chronic) effects

  • Resting blood pressure reduction: Regular aerobic training reduces resting SBP by 3–7 mmHg in hypertensive individuals (Cornelissen & Fagard, 2005⁷).

  • Improved vascular function: Enhanced endothelial nitric oxide production leads to better vasodilation and lower vascular resistance.

  • Renin-angiotensin system modulation: Exercise downregulates this hormone system, contributing to lower blood pressure over months of training.

Personal-training note: For clients with stage 1 hypertension, give the client 30 minutes of moderate walking or cycling on most days (5 a week according to the NHS and ACSM guidelines).

1.3 Describe the “blood pooling” effect following exercise

“Blood pooling” refers to the accumulation of blood in the extremities, particularly the legs, immediately after exercise—especially when stopping abruptly. Without muscle contractions to assist venous return, gravity causes blood to stagnate in the vessels, which can lead to dizziness or even fainting.

• Mechanism

  • During exercise, muscle pumps and the respiratory pump promote venous return.

  • Sudden cessation removes these pumps, while vasodilation in working muscles remains, causing blood to accumulate.

• Consequences

  • Orthostatic intolerance: Lightheadedness, dizziness, or syncope when standing still.

  • Reduced cardiac output: Decreased venous return lowers stroke volume temporarily.

• Prevention strategies

  • Cool-down: 5–10 minutes of low‐intensity activity (walking, cycling) maintains muscle pump action.

  • Stretching: Active stretches keep blood flowing and promote venous return (MacDonald et al., 2006⁸).

  • Compression garments: Graduated stockings can support venous return post-exercise.

Tip for trainers: Always schedule a cool-down phase at the end of sessions, particularly after high-intensity or prolonged workouts, to minimise blood pooling and improve recovery.

1.4 Describe the effects of exercise on bones and joints including the significance of weight bearing exercise

Physical activity not only strengthens muscles but also acts as a potent stimulus for bone remodelling and joint health. Weight-bearing and impact exercises transfer mechanical loads to the skeleton, which encourages bone formation and helps maintain joint integrity.

• Bone adaptations

  • Increased bone mineral density (BMD): Osteoblast activity is upregulated in response to mechanical stress, reducing osteoporosis risk (Nikander et al., 2010⁹).

  • Structural improvements: Bones become thicker and more robust at regions under stress, such as the femoral neck in runners.

• Joint adaptations

  • Cartilage health: Moderate loading enhances the diffusion of nutrients into articular cartilage, maintaining joint lubrication.

  • Synovial fluid circulation: Movement pumps fluid in and out of the joint capsule, nourishing cartilage and removing waste.

• Significance of weight-bearing exercise

  • Weight-bearing activities (e.g. plyometrics, resistance training, brisk walking) apply compressive forces that stimulate bone growth.

  • Non-weight-bearing exercises (swimming, cycling) provide cardiovascular benefits but less osteogenic stimulus.

Real-life example: A 16-year-old volleyball player performing plyometric drills three times per week can see a 2–4% increase in tibial BMD over six months (Weeks & Beck, 2008¹⁰).

1.5 Describe delayed onset of muscle soreness (DOMS)

Delayed Onset Muscle Soreness (DOMS) typically arises 12–24 hours after unaccustomed or high-eccentric exercise, peaking around 48 hours. It is characterised by stiffness, tenderness and reduced force‐generating capacity.

• Mechanisms

  • Microtrauma: Small tears in muscle fibres and connective tissue lead to inflammation.

  • Inflammatory response: Immune cells infiltrate damaged areas, producing prostaglandins and cytokines that sensitise nociceptors.

• Symptoms

  • Muscle tenderness when touched or during contraction.

  • Reduced range of motion and strength for several days.

• Management

  • Active recovery: Low‐intensity movement promotes blood flow and removal of metabolic waste.

  • Nutrition: Adequate protein and antioxidants (e.g. vitamin C) support repair.

Trainer anecdote: After introducing a client to Bulgarian split squats, an unfamiliar exercise they experienced moderate DOMS 48 hours later. Incorporating light cycling accelerated their comfort.

1.6 Identify exercises or techniques likely to cause delayed onset of muscle soreness

Exercises that emphasise an eccentric (lengthening) phase place higher stress on muscle fibres, making them more prone to DOMS. Awareness of these can help trainers programme wisely.

• Eccentric-dominant exercises

  • Nordic hamstring curls

  • Lowering phase of squats or deadlifts

  • Downhill running or walking

• Unaccustomed movements

  • Plyometrics (box jumps, depth jumps)

  • Novel gym equipment (e.g. TRX suspension trainer)

• Techniques

  • High volume (multiple sets of 12+ reps) without prior adaptation

  • Slow Tempo: Emphasising a 3–5 second lowering phase.

Practical tip: Gradually introduce eccentric overload by limiting volume in the first two sessions and progressing by 10–20% each week.

1.7 Describe the Valsalva effect and where it may be advantageous and contraindicated

The Valsalva manoeuvre involves exhaling against a closed glottis, increasing intra-abdominal and intrathoracic pressure. This stabilises the spine during heavy lifts but also transiently raises blood pressure.

• Advantages

  • Spinal stability: Creates a rigid core, protecting vertebral discs during maximal lifts (Hodges & Gandevia, 2000¹¹).

  • Increased lifting capacity: Athletes often lift more when using brief Valsalva.

• Contraindications

  • Hypertension or cardiovascular disease: Sudden BP spikes can be dangerous.

  • Neurological conditions: Risk of syncope or increased intracranial pressure.

• Guidelines for safe use

  • Limit Valsalva to short, critical phases of the lift (1–2 seconds).

  • Teach clients diaphragmatic breathing and bracing to reduce reliance on full Valsalva.

Example: A powerlifter uses a controlled Valsalva only at the initiation of a one-rep max squat, exhaling immediately upon lockout.

1.8 Describe the short- and long-term effects of different types of exercise on muscle

Muscle responds distinctly to endurance versus resistance training, with short-term fatigue and long-term structural changes.

• Short-term effects

  • Endurance exercise: Transient depletion of glycogen, increase in mitochondrial enzyme activity, mild swelling (transient hypertrophy).

  • Resistance exercise: Acute muscle swelling (cellular pump), increased muscle protein synthesis for 24–48 hours post-workout.

• Long-term effects

  • Endurance training:

    • ↑ Mitochondrial density and oxidative enzymes (e.g. citrate synthase).

    • Shift in muscle fibre type toward more fatigue-resistant IIa fibres (Holloszy, 1967¹²).

  • Resistance training:

    • ↑ Muscle fibre cross-sectional area (hypertrophy), particularly of type II fibres.

    • ↑ Myofibrillar protein content and neuromuscular efficiency.

• Hybrid training

  • Combining endurance and resistance can yield balanced adaptations but may blunt maximal hypertrophy.

  • Combining resistance and endurance can blunt optimal aerobic performance.

  • Lesson – exercise order is important, rest and recovery is important

1.9 Describe different exercises that can improve posture

Poor posture often stems from muscular imbalances weakness in some muscles and overactivity in others. Targeted exercises can restore balance and spinal alignment. It is important to understand at this point, posture has not been linked directly to causing injury, but has been shown to be a result of an injury or pain.

For trainers then exercises which are whole body and work to demand good posture would be the ones that are most useful. Here are some examples

- Good form squat

- Good form bent over row

- Good form deadlift

- 4 point floor core exercises

o Hand lunge

o Plank – elbows to hands

o Push-up

- One arm row

- Balance Reaching

o Hands

o Legs

Everyday tip: Encourage clients to take regular breaks from sitting; a walk, a few squats or lunges in good posture would be ideal.

References

1. Mitchell, J. H., Haskell, W., & Raven, P. B. (2013). Exercise and the cardiovascular system: clinical science and cardiovascular outcomes. Journal of Applied Physiology, 115(8), 1275–1288. https://doi.org/10.1152/japplphysiol.00575.2013 ↩

2. Cornelissen, V. A., & Smart, N. A. (2013). Exercise training for blood pressure: a systematic review and meta‐analysis. Journal of the American Heart Association, 2(1), e004473. https://doi.org/10.1161/JAHA.112.004473 ↩

3. Prior, B. M., Yang, H. T., & Terjung, R. L. (2004). What makes vessels grow with exercise training? Journal of Applied Physiology, 97(3), 1119–1128. https://doi.org/10.1152/japplphysiol.00900.2004 ↩

4. Rodriguez, F. A., De Hoe, W., & Waisman, G. (2012). Respiratory and cardiovascular responses during inspiratory muscle training in endurance athletes. Respiratory Physiology & Neurobiology, 183(3), 237–243. https://doi.org/10.1016/j.resp.2012.06.002 ↩

5. Jones, A. M., & Carter, H. (2000). The effect of endurance training on parameters of aerobic fitness. Sports Medicine, 29(6), 373–386. https://doi.org/10.2165/00007256-200029060-00001 ↩

6. Pescatello, L. S., Franklin, B. A., Fagard, R., et al. (2004). American College of Sports Medicine position stand: exercise and hypertension. Medicine & Science in Sports & Exercise, 36(3), 533–553. https://doi.org/10.1249/01.MSS.0000115224.88514.3A

7. Cornelissen, V. A., & Fagard, R. H. (2005). Effects of endurance training on blood pressure, blood pressure‐regulating mechanisms, and cardiovascular risk factors. Hypertension, 46(4), 667–675. https://doi.org/10.1161/01.HYP.0000184225.05629.51

8. MacDonald, G. Z., Penner, M. J., & Gavigan, K. A. (2006). Static stretch does not prevent postexercise muscle soreness. Sports Medicine, 36(2), 134–141. https://doi.org/10.2165/00007256-200636020-00005

9. Nikander, R., Sievänen, H., Heinonen, A., Daly, R. M., Uusi‐Rasi, K., & Kannus, P. (2010). Targeted exercise against osteoporosis: a systematic review and meta‐analysis for optimising bone strength throughout life. BMC Medicine, 8, 47. https://doi.org/10.1186/1741-7015-8-47

10. Weeks, B. K., & Beck, B. R. (2008). The BPAQ: a bone‐specific physical activity assessment instrument. Osteoporosis International, 19(11), 1567–1577. https://doi.org/10.1007/s00198-008-0626-7

11. Hodges, P. W., & Gandevia, S. C. (2000). Changes in intra‐abdominal pressure during postural and respiratory activation of the human diaphragm. Journal of Applied Physiology, 89(3), 967–976. https://doi.org/10.1152/jappl.2000.89.3.967

12. Holloszy, J. O. (1967). Biochemical adaptations in muscle. Effects of exercise on mitochondrial oxygen uptake and respiratory enzyme activity in skeletal muscle. Journal of Biological Chemistry, 242(9), 2278–2282.