Which sign most clearly distinguishes heat stroke from heat exhaustion?

Disturbed mental function, such as confusion or collapse, with a very high core temperature

Assertion (A): Women and men show a similar relative increase in strength with resistance training. Reason (R): Women have higher testosterone levels than men. Choose the correct option.

Both A and R are true, and R is the correct explanation of A

Both A and R are true, but R is not the correct explanation of A

Immediately after an ankle sprain, which modality is appropriate and why?

Cold, because it constricts blood vessels and reduces pain and swelling

Deep massage, because it removes the injury quickly

Ultrasound heating at full intensity

Cold, because it constricts blood vessels and reduces pain and swelling

Heat, because it dilates vessels and increases swelling

At the 1968 Olympics in Mexico City (about 2,240 m), endurance performances were generally poorer while sprint and jump performances were often better. The best explanation is that

lower oxygen pressure reduced VO2max, while thinner air reduced aerodynamic drag on short, anaerobic efforts

the percentage of oxygen in the air is lower at altitude

gravity is much weaker at 2,240 m

altitude increases muscle glycogen, helping sprinters

lower oxygen pressure reduced VO2max, while thinner air reduced aerodynamic drag on short, anaerobic efforts

Which statements about ageing and exercise are correct? Select all that apply.

Balance training such as tai chi reduces the risk of falls

Resistance training can increase strength and muscle mass even in older adults

Maximal heart rate rises with age

Type I fibres are lost first in sarcopenia

Balance training such as tai chi reduces the risk of falls

Resistance training can increase strength and muscle mass even in older adults

Exercise Physiology III: Environmental Influences on Human Physiology in Exercise, Women in Sport, their Trainability, Physiological Sex Differences and the Special Problems of Women Athletes, Ageing and Healthful Ageing, the Physiological Responses to Therapeutic Modalities and Rehabilitation, Ergogenic Aids and Massage

The last part of Unit II applies physiology to conditions and populations: exercise in heat, cold, altitude and polluted air; women in sport, with the differences between the sexes that matter for training and the particular problems of women athletes; the physiology of ageing and how activity slows it; the physiological effects of cold, heat, water and electrical therapies and the stages of rehabilitation; and ergogenic aids, discussed academically, with their status under the World Anti-Doping Code and the Prohibited List stated accurately, followed by massage and its manipulations. Health content is written at textbook level, as education, not personal medical advice.

1. Environmental influences: heat, cold, altitude and pollution

Exercise raises heat production many times over, and the body loses heat by radiation, conduction, convection and, above all in exercise, the evaporation of sweat. In hot, humid conditions evaporation is limited, core temperature rises, sweat losses dehydrate the athlete and blood is shared between muscle and skin, so endurance performance falls. The heat illnesses range from heat cramps and heat syncope to heat exhaustion (fatigue, dizziness, heavy sweating, core temperature up to about 40 °C) and heat stroke, a medical emergency in which core temperature exceeds about 40 °C with disturbed mental function, and which is treated by immediate whole-body cooling, ideally cold-water immersion, and emergency care. Heat acclimatisation over about 10–14 days of training in the heat increases plasma volume, starts sweating earlier and more copiously with more dilute sweat, and lowers heart rate and core temperature at a given workload. The wet-bulb globe temperature (WBGT) index, which combines temperature, humidity and radiant heat, guides decisions to modify or cancel events.

In cold conditions the body conserves heat by constricting skin blood vessels and generates it by shivering; risks are hypothermia (core temperature below 35 °C) and frostbite, worsened by wind chill and wet clothing. Layered clothing and keeping dry are the main defences. At altitude the barometric pressure falls, and so does the partial pressure of oxygen (about 21 per cent of barometric pressure), so less oxygen reaches the blood (hypoxia). The immediate responses are faster breathing and a higher heart rate at a given workload; VO2max falls and endurance events suffer, while sprints and jumps can benefit from the thinner air, as at the 1968 Mexico City Olympics (about 2,240 m), where Bob Beamon long-jumped 8.90 m. Acclimatisation over weeks raises erythropoietin (EPO) secretion and red-cell mass. The "live high, train low" model uses altitude residence for the blood adaptation and low-altitude training to maintain intensity. Acute mountain sickness (headache, nausea, insomnia) is the common altitude illness; its severe forms, pulmonary and cerebral oedema, need descent.

Air pollution matters because exercise multiplies the volume of air breathed and shifts breathing to the mouth, bypassing nasal filtering. Fine particulate matter (PM2.5), ozone, sulphur dioxide, nitrogen oxides and carbon monoxide irritate the airways, can provoke exercise-induced bronchoconstriction in asthmatic athletes and, in the case of carbon monoxide, bind haemoglobin and reduce oxygen transport. Practical measures are to check the Air Quality Index, avoid exercise near heavy traffic and at peak pollution hours, move sessions indoors on bad days and reduce intensity.

⚠️ Heat exhaustion and heat stroke are not the same

The distinguishing sign of heat stroke is disturbed mental function (confusion, collapse, unconsciousness) with a core temperature above about 40 °C; it is life-threatening and needs immediate cooling and emergency care. Heat exhaustion, with heavy sweating, weakness and dizziness but clear mind, is treated by rest in the shade, cooling and fluids.

2. Women in sport: trainability, sex differences and special problems

After puberty, men on average are taller and heavier with more muscle mass, a lower percentage of body fat, larger hearts and lungs, higher haemoglobin concentration and higher absolute VO2max. Women's absolute strength averages roughly half to two-thirds of men's in the upper body and about two-thirds to three-quarters in the lower body, but strength relative to lean muscle mass is similar, because muscle quality is essentially the same. Women have a wider pelvis and a larger Q-angle, the angle between the pull of the quadriceps and the patellar tendon. These differences largely explain the performance gap of about 10 per cent in elite running and swimming. Trainability, the relative response to training, is similar in both sexes: women gain strength, endurance and VO2max in the same proportion as men, though hypertrophy is smaller in absolute terms because of lower testosterone.

Special problems of women athletes include the female athlete triad, the interrelation of low energy availability (with or without disordered eating), menstrual dysfunction (up to amenorrhoea) and low bone mineral density, which raises the risk of stress fractures; in 2014 the IOC broadened the concept as Relative Energy Deficiency in Sport (RED-S), which recognises that low energy availability affects many body systems and occurs in men too. Iron-deficiency anaemia is more common because of menstrual losses. Anterior cruciate ligament injuries are several times more frequent in women in jumping and cutting sports, linked to anatomy, hormones and landing mechanics, and neuromuscular training programmes reduce the risk. Exercise during the menstrual cycle is generally safe and performance effects vary between individuals; moderate exercise in an uncomplicated pregnancy is recommended under medical guidance. Socio-cultural barriers, such as lack of facilities, safety concerns and family attitudes, are as real as the physiological ones.

3. Ageing: physiological consequences, lifestyle management and healthful ageing

With age maximal heart rate falls (the basis of the conventional estimate 220 − age), VO2max declines, by roughly 10 per cent per decade after about 25–30 years in sedentary people and about half that in those who stay active, muscle mass and strength decline (sarcopenia), with type II fibres lost first, bone mineral density falls (osteopenia and osteoporosis, especially in women after menopause), joints stiffen and flexibility falls, balance and reaction time worsen, body fat rises and basal metabolic rate falls. Much of what was once attributed to age is in fact the effect of inactivity.

Healthful ageing depends on lifestyle management. Regular aerobic activity slows the decline in VO2max; resistance training at any age increases strength and muscle mass and protects bone; balance training such as tai chi and yoga reduces falls; flexibility exercise maintains range of motion. The World Health Organization's 2020 guidelines advise adults, including older adults, to do at least 150–300 minutes of moderate or 75–150 minutes of vigorous aerobic activity a week, with muscle-strengthening activity on two or more days, and older adults to add balance and strength activities on three or more days a week to prevent falls. Nutrition with adequate protein, calcium and vitamin D, avoidance of tobacco, moderation in alcohol, sleep, social engagement and mental activity complete the picture.

4. Therapeutic modalities, rehabilitation and massage

Therapeutic modalities are physical agents used to relieve pain, control swelling and promote healing. Cryotherapy (ice packs, ice massage, cold-water immersion) causes vasoconstriction, slows nerve conduction and reduces pain and metabolic demand, and is used in the acute stage of soft-tissue injury. Thermotherapy (hot packs, warm water, infrared) causes vasodilation, increases tissue extensibility and relaxes muscle, and is used in later stages and for stiffness, never on a fresh injury. Contrast baths alternate the two. Hydrotherapy uses water's buoyancy and resistance for exercise with reduced load. Electrotherapy includes TENS (transcutaneous electrical nerve stimulation) for pain relief, therapeutic ultrasound, which produces deep heating, and neuromuscular electrical stimulation to activate muscles. The acute management of soft-tissue injury has moved from RICE (rest, ice, compression, elevation) to PRICE and POLICE, which replaces rest with "optimal loading", and to PEACE and LOVE (2019), which adds education, load, optimism, vascularisation and exercise.

Rehabilitation restores function after injury in stages: controlling pain and inflammation; restoring range of motion; restoring strength and endurance, progressing from isometric to isotonic and functional exercise; restoring proprioception, balance and coordination; sport-specific training; and a graded return to play once criteria are met. The physiological basis is that tissues heal in overlapping phases, inflammation, proliferation and remodelling, and that controlled, progressive loading guides remodelling, while prolonged immobilisation causes atrophy, stiffness and loss of bone.

Massage is the systematic manipulation of soft tissues. Its classical manipulations are effleurage (long, gliding strokes, usually towards the heart, used to begin and end), petrissage (kneading, wringing and picking up of muscle), friction (small, deep circular or cross-fibre movements over a tendon or ligament), tapotement (percussive strokes such as hacking, cupping, beating and pounding) and vibration or shaking. Its physiological responses include increased local blood flow and skin temperature, reduced muscle tension and a sense of relaxation, pain relief and improved mood; claims that massage greatly speeds lactate removal are not well supported, and its benefits for recovery appear to be partly psychological. It is avoided over acute injuries, infections, open wounds, fractures and suspected blood clots.

5. Ergogenic aids and anti-doping

An ergogenic aid is any substance, device or practice that enhances performance beyond what training alone achieves. They are classified as nutritional (carbohydrate loading, caffeine, creatine, sodium bicarbonate, beta-alanine, nitrate from beetroot juice), pharmacological (anabolic steroids, stimulants, peptide hormones), physiological (blood doping, altitude training, warm-up), mechanical or biomechanical (lighter shoes, aerodynamic clothing and equipment) and psychological (hypnosis, imagery, music). Among the legal nutritional aids, creatine raises muscle phosphocreatine and helps repeated high-intensity efforts, caffeine improves endurance and alertness, and bicarbonate and beta-alanine buffer acid in efforts of about one to several minutes; all three are permitted. Caffeine was removed from the Prohibited List in 2004 and is on WADA's monitoring programme. Supplements carry a real risk of contamination with prohibited substances, and under strict liability the athlete is responsible for whatever is found in their sample.

The World Anti-Doping Code, first adopted in 2003 and in force since 2004, harmonises anti-doping rules across sports and countries, and WADA publishes the Prohibited List every year. Substances and methods prohibited at all times include anabolic agents such as anabolic steroids (S1), peptide hormones and growth factors such as erythropoietin (EPO) and human growth hormone (S2), beta-2 agonists (S3, with specific exceptions for inhaled salbutamol and some others within stated limits), hormone and metabolic modulators (S4, which since 2016 has included meldonium) and diuretics and masking agents (S5), together with manipulation of blood and blood components (M1, including blood doping), chemical and physical manipulation (M2) and gene and cell doping (M3). Stimulants, narcotics, cannabinoids and glucocorticoids are prohibited in competition (S6–S9), and beta-blockers are prohibited in particular sports such as archery and shooting. An athlete who needs a prohibited medicine can apply for a Therapeutic Use Exemption. In India the National Anti-Doping Act 2022 gave statutory status to the National Anti-Doping Agency and the National Dope Testing Laboratory and created a national board for anti-doping in sport. Beyond breaking rules, doping carries serious health risks: anabolic steroids affect the liver, heart and hormones, EPO and blood doping thicken the blood and raise the risk of clots and stroke, and stimulants strain the heart.

Aid	Main effect	Status under the Prohibited List
Creatine	Raises phosphocreatine; repeated sprints	Permitted
Caffeine	Alertness, endurance	Permitted (removed 2004; monitored)
Sodium bicarbonate	Buffers acid	Permitted
Anabolic steroids	Muscle mass and strength	Prohibited at all times (S1)
EPO	Raises red-cell mass	Prohibited at all times (S2)
Blood doping	Raises red-cell mass	Prohibited method (M1)
Beta-blockers	Steady hands, lower heart rate	Prohibited in particular sports such as archery and shooting

Key takeaways

Heat stroke (core above about 40 °C with disturbed mental function) is an emergency; acclimatisation over 10–14 days expands plasma and improves sweating; altitude lowers oxygen pressure and stimulates EPO.
Women have lower absolute strength and VO2max but similar trainability; the female athlete triad, now RED-S, iron deficiency and ACL injury are their special problems.
Ageing lowers maximal heart rate, VO2max, muscle and bone, but much of the decline is inactivity; aerobic, strength and balance training keep older adults healthy.
Cold constricts vessels and suits acute injury; heat dilates them and suits later stages; massage uses effleurage, petrissage, friction, tapotement and vibration.
Creatine, caffeine and bicarbonate are permitted; anabolic steroids, EPO and blood doping are prohibited at all times; NADA and the NDTL became statutory under the National Anti-Doping Act 2022.

Practice questions (10)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

Oxygen makes up about 21 per cent of the air. At an altitude where the barometric pressure is 500 mmHg, what is the partial pressure of oxygen in mmHg? Type the number.
Numerical answer — type the value.
Show answer
Answer: 105
Partial pressure of oxygen = 0.21 × 500 = 105 mmHg, against about 159 mmHg at sea level (0.21 × 760). The percentage of oxygen does not change with altitude; the total pressure does, which is why hypoxia occurs.
A 70 kg footballer weighs 68.6 kg after a training session in the heat, having drunk nothing. What percentage of body mass has he lost? Type the number.
Numerical answer — type the value.
Show answer
Answer: 2
Loss = 70 − 68.6 = 1.4 kg; 1.4 ÷ 70 × 100 = 2 per cent, the level at which endurance performance begins to be impaired. Each kilogram lost represents roughly a litre of fluid to be replaced.
Which sign most clearly distinguishes heat stroke from heat exhaustion?
1. Thirst
2. Mild muscle cramps
3. Heavy sweating
4. Disturbed mental function, such as confusion or collapse, with a very high core temperature
Show answer
Answer: D — Disturbed mental function, such as confusion or collapse, with a very high core temperature
Heat stroke is marked by central nervous system disturbance with a core temperature above about 40 °C and needs immediate cooling and emergency care. Sweating, thirst and cramps occur in milder heat illness too.
The female athlete triad consists of low energy availability, menstrual dysfunction and
1. excess muscle mass
2. high haemoglobin
3. low bone mineral density
4. high blood pressure
Show answer
Answer: C — low bone mineral density
The triad is low energy availability, menstrual dysfunction and low bone mineral density, which raises stress-fracture risk. The IOC broadened it in 2014 into RED-S, which also recognises effects on other systems and in men.
Assertion (A): Women and men show a similar relative increase in strength with resistance training. Reason (R): Women have higher testosterone levels than men. Choose the correct option.
1. Both A and R are true, and R is the correct explanation of A
2. Both A and R are true, but R is not the correct explanation of A
3. A is true, but R is false
4. A is false, but R is true
Show answer
Answer: C — A is true, but R is false
A is true: trainability is similar and relative strength gains are comparable. R is false: women have much lower testosterone, which is why their absolute hypertrophy is smaller even though relative gains are similar.
Which of the following are prohibited at all times under the WADA Prohibited List? Select all that apply.
1. Erythropoietin (EPO)
2. Blood doping
3. Creatine monohydrate
4. Anabolic steroids
Show answer
Answer: A — Erythropoietin (EPO); B — Blood doping; D — Anabolic steroids
EPO (S2), anabolic steroids (S1) and blood doping (M1) are prohibited in and out of competition. Creatine is a permitted nutritional ergogenic aid, although any supplement risks contamination.
In which massage manipulation is muscle kneaded, wrung and picked up?
1. Effleurage
2. Vibration
3. Tapotement
4. Petrissage
Show answer
Answer: D — Petrissage
Petrissage is kneading and wringing. Effleurage is long gliding strokes that begin and end a massage, tapotement is percussion such as hacking and cupping, and vibration is shaking.
Immediately after an ankle sprain, which modality is appropriate and why?
1. Deep massage, because it removes the injury quickly
2. Ultrasound heating at full intensity
3. Cold, because it constricts blood vessels and reduces pain and swelling
4. Heat, because it dilates vessels and increases swelling
Show answer
Answer: C — Cold, because it constricts blood vessels and reduces pain and swelling
In the acute stage cold is used for its vasoconstriction and pain relief, alongside protection, compression and elevation. Heat and deep massage increase blood flow and can worsen fresh swelling, so they belong to later stages.
At the 1968 Olympics in Mexico City (about 2,240 m), endurance performances were generally poorer while sprint and jump performances were often better. The best explanation is that
1. the percentage of oxygen in the air is lower at altitude
2. gravity is much weaker at 2,240 m
3. altitude increases muscle glycogen, helping sprinters
4. lower oxygen pressure reduced VO2max, while thinner air reduced aerodynamic drag on short, anaerobic efforts
Show answer
Answer: D — lower oxygen pressure reduced VO2max, while thinner air reduced aerodynamic drag on short, anaerobic efforts
The fraction of oxygen stays about 21 per cent; its partial pressure falls, cutting VO2max and hurting endurance events. Short events depend little on oxygen and gain from lower air density, which reduces drag. The change in gravity at that height is negligible.
Which statements about ageing and exercise are correct? Select all that apply.
1. Maximal heart rate rises with age
2. Type I fibres are lost first in sarcopenia
3. Balance training such as tai chi reduces the risk of falls
4. Resistance training can increase strength and muscle mass even in older adults
Show answer
Answer: C — Balance training such as tai chi reduces the risk of falls; D — Resistance training can increase strength and muscle mass even in older adults
Strength training works at any age and balance training reduces falls. Maximal heart rate falls with age, which is the basis of 220 − age, and sarcopenia affects type II fibres most.