第一次跑半马或全马，身体要准备什么

参考文献 · 28

1. Spina, R. J., Chi, M. M., Hopkins, M. G., Nemeth, P. M., Lowry, O. H., & Holloszy, J. O. (1996). Mitochondrial enzymes increase in muscle in response to 7-10 days of cycle exercise. Journal of Applied Physiology, 80(6), 2250-2254. Background in the abstract: endurance training raises mitochondrial enzyme activity, and 'one consequence of this adaptation is that there is a decreased reliance on carbohydrate utilization with a concomitant increase in fat utilization, resulting in an improvement in endurance capacity.' Twelve subjects (6 men, 6 women) cycled 2 h/day at 60-70% of peak oxygen uptake for 7 (n = 5) or 10 days (n = 7), with no separate control group. Peak oxygen uptake rose 9% (2.97 to 3.24 L/min), blood lactate was lower at the same absolute work rates, and citrate synthase, beta-hydroxyacyl-CoA dehydrogenase, mitochondrial thiolase and carnitine acetyltransferase rose by approximately 30%. Conclusion: 'in humans, as in rats, the adaptive increase in mitochondrial enzymes in skeletal muscle occurs fairly rapidly in response to exercise training'; the results give no support for the claim that it is delayed for more than 2 weeks (abstract, PMID 8806937). 10.1152/jappl.1996.80.6.2250
2. Murias, J. M., Kowalchuk, J. M., & Paterson, D. H. (2010). Time course and mechanisms of adaptations in cardiorespiratory fitness with endurance training in older and young men. Journal of Applied Physiology, 108(3), 621-627. Eight older (68 years) and 8 young (23 years) men cycled three times a week for 45 min at about 70% of maximal oxygen uptake for 12 weeks, tested every 3 weeks. 'VO2max increased within 3 wk with further increases observed posttraining in both O (+31%) and Y (+18%)'; maximal cardiac output and stroke volume were higher after 3 weeks with further increases after 9 weeks. Early adaptations (first 3 weeks) relied mainly on a widened arterial-venous oxygen difference (about 66%), later ones on greater maximal cardiac output. Conclusion: with short-term training both groups significantly increased VO2max, but the share explained by cardiac output and oxygen extraction followed a different pattern by age (abstract, PMID 20056848). 10.1152/japplphysiol.01152.2009
3. Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., & Kjaer, M. (2013). Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C. The FASEB Journal, 27(5), 2074–2079. Bomb-pulse 14C in 28 forensic Achilles tendon core samples and 4 muscle samples: the tendon core retained 14C levels matching the atmosphere several decades before sampling, showing very limited tissue turnover, while muscle showed continuous turnover (abstract, PMID 23401563). 10.1096/fj.12-225599
4. Bohm, S., Mersmann, F., & Arampatzis, A. (2015). Human tendon adaptation in response to mechanical loading: a systematic review and meta-analysis of exercise intervention studies on healthy adults. Sports Medicine - Open, 1(1), 7. 27 studies (37 interventions of at least 8 weeks, 264 healthy adults aged 18-50, Achilles or patellar tendon): stiffness SMD 0.70, Young's modulus SMD 0.69, cross-sectional area SMD 0.24, all significant. Stiffness adaptation depended on loading intensity but not on contraction type; 'Although not significantly different, SMD was higher for interventions with longer duration (≥12 weeks).' Conclusion: 'tendons are highly responsive to diverse loading regimens. However, the data strongly suggests that loading magnitude in particular plays a key role for tendon adaptation in contrast to muscle contraction type' (abstract, PMID 27747846). 10.1186/s40798-015-0009-9
5. Damsted, C., Parner, E. T., Sørensen, H., Malisoux, L., Hulme, A., & Nielsen, R. Ø. (2019). The association between changes in weekly running distance and running-related injury: preparing for a half marathon. Journal of Orthopaedic & Sports Physical Therapy, 49(4), 230-238. Prospective cohort of 261 healthy runners preparing for a half marathon, followed for 14 weeks with GPS-recorded running. 56 participants (21.5%) sustained a running-related injury. Twenty-one days in, significantly more runners were injured when they increased weekly running distance by 20% to 60% than by less than 20% (cumulative risk difference 22.6%, 95% CI 0.9% to 44.3%, P = .041); no significant difference was found after 56 and 98 days, and the running schedule followed did not modify the association. Conclusion: 'Significantly more runners were injured 21 days into the study period when they increased their weekly running distances by 20% to 60% compared with those who increased their distances by less than 20%' (abstract, PMID 30526231). 10.2519/jospt.2019.8541
6. Hew-Butler, T., Rosner, M. H., Fowkes-Godek, S., Dugas, J. P., Hoffman, M. D., Lewis, D. P., Maughan, R. J., Miller, K. C., Montain, S. J., Rehrer, N. J., Roberts, W. O., Rogers, I. R., Siegel, A. J., Stuempfle, K. J., Winger, J. M., & Verbalis, J. G. (2015). Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clinical Journal of Sport Medicine, 25(4), 303–320. Full text read 2026-09-24 (simultaneous BJSM publication, 49(22), 1432, via a Wayback snapshot of 10 October 2024; PubMed has no abstract, PMID 26102445): the single most important risk factor is sustained excessive intake of water, sports drinks or other hypotonic fluids beyond sweat, respiratory and renal losses; all sports drinks are hypotonic (sodium about 10-38 mmol/L), so overdrinking them is not protective. Using thirst to guide drinking should limit overdrinking while preventing excessive dehydration (Grade 1C); earlier advice to drink before thirst was meant for high sweat rates; fluid deficits up to about 3% of body mass are tolerated in cool to temperate conditions. Sodium supplements cannot prevent EAH when fluid intake is excessive (Grade 1C). Treatment: symptom severity, not the sodium value, guides therapy (Grade 1A); restrict hypotonic and isotonic fluids until urinating; severe EAH with encephalopathy gets an immediate 100 mL bolus of 3% NaCl, repeated up to twice (about 10-min intervals) if there is no improvement, without waiting for a lab value (Grade 1B); IV hypotonic fluids, lactated Ringer's or normal saline are contraindicated in confirmed dilutional EAH. Travel and meals for the panel were funded by CrossFit, Inc. 10.1097/JSM.0000000000000221
7. NHS. (2026). Heart attack: symptoms. Symptoms can include chest pain that may feel like crushing or squeezing on the chest and may spread to the arm, neck and jaw; feeling short of breath; feeling or being sick; feeling like indigestion; sweating; and pale, blue or grey skin. Call 999 for chest pain that feels tight or like squeezing, or that spreads to the arms, neck or jaw, with severe difficulty breathing, or if someone becomes unresponsive. A heart attack needs emergency treatment in hospital (page last reviewed 31 March 2026). www.nhs.uk/conditions/heart-attack/symptoms
8. NHS. (2026). Fainting (page last reviewed 17 August 2026). Fainting is when you pass out for a short time; it is not usually serious, but anyone who has fainted should see a GP to find out what might have caused it. Causes can include standing up too quickly (which could be a sign of low blood pressure), not eating or drinking enough, being too hot, being very upset or in severe pain, heart problems, and taking drugs or drinking too much alcohol. Call 999 if someone is not breathing, cannot be woken up within 1 minute, has not fully recovered or has difficulty with speech or movement, has chest pain or a pounding, fluttering or irregular heartbeat (palpitations), has seriously hurt themselves before or after fainting, is shaking or jerking (a seizure), fainted while exercising, or fainted while lying down; do not drive yourself to A&E. If you feel about to faint: lie down with your legs raised, or if you cannot, sit with your head lowered between your knees; drink some water; cross your legs while standing up or rock up and down on your toes; clench your fists. If you see someone faint: check whether they respond by gently shaking their shoulders and asking loudly; if not, shout for help and tilt back the head and lift the chin; listen for breathing for at least 10 seconds; if they are breathing normally, lay them on their back and raise their legs (on their side if pregnant, especially over 28 weeks); they usually wake up within 30 seconds. www.nhs.uk/conditions/fainting
9. Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276-291. Review: descriptive studies of nationally or internationally competitive endurance athletes training 10 to 13 times per week 'seem to converge on a typical intensity distribution in which about 80% of training sessions are performed at low intensity (2 mM blood lactate), with about 20% dominated by periods of high-intensity work, such as interval training at approx. 90% VO2max.' Training-intensification studies in already well-trained athletes 'do not provide any convincing evidence that a greater emphasis on high-intensity interval training in this highly trained athlete population gives long-term performance gains.' The predominance of low-intensity, long-duration training combined with fewer highly intensive bouts may be complementary (abstract, PMID 20861519). 10.1123/ijspp.5.3.276
10. Esteve-Lanao, J., Foster, C., Seiler, S., & Lucia, A. (2007). Impact of training intensity distribution on performance in endurance athletes. Journal of Strength and Conditioning Research, 21(3), 943-949. Twelve sub-elite endurance runners (mostly 5,000-m and cross-country specialists) were randomly assigned to two heart-rate-controlled programs for about 5 months. Share of training time in zone 1 (below the ventilatory threshold) and zone 2: 80.5% and 11.8% in the Z1 group versus 66.8% and 24.7% in the Z2 group, with high-intensity time kept similar. The improvement in a simulated 10.4-km cross-country race was significantly greater in Z1 (-157 s) than in Z2 (-121.5 s). Conclusion: the results support 'the value of a relatively large percentage of low-intensity training over a long period (approximately 5 months), provided that the contribution of high-intensity training remains sufficient' (abstract, PMID 17685689). 10.1519/R-19725.1
11. Reed, J. L., & Pipe, A. L. (2014). The talk test: a useful tool for prescribing and monitoring exercise intensity. Current Opinion in Cardiology, 29(5), 475-480. 'In healthy adults and patients with cardiovascular disease, comfortable speech is likely possible (equivocal or last positive talk test stage) when exercise intensity is below the ventilatory or lactate threshold, and not likely possible (negative talk test stage) when exercise intensity exceeds the ventilatory or lactate threshold.' The talk test has been consistent across walking, jogging, cycling, elliptical trainer and stair stepper, and may not be practical for high-intensity interval training. Summary: it 'is a valid, reliable, practical and inexpensive tool for prescribing and monitoring exercise intensity in competitive athletes, healthy active adults and patients with cardiovascular disease' (abstract, PMID 25010379). 10.1097/HCO.0000000000000097
12. Hawley, J. A., Schabort, E. J., Noakes, T. D., & Dennis, S. C. (1997). Carbohydrate-loading and exercise performance: an update. Sports Medicine, 24(2), 73-81. Review: little or no effect of raising pre-exercise muscle glycogen above normal resting values on a single exhaustive bout of high-intensity exercise lasting less than 5 minutes, 'nor is there any benefit of increasing starting muscle glycogen content on moderate-intensity running or cycling lasting 60 to 90 minutes', because substantial glycogen remains in the working muscles at the end. 'However, elevated starting muscle glycogen content will postpone fatigue by approximately 20% in endurance events lasting more than 90 minutes. During this type of exercise, exhaustion usually coincides with critically low (25 mmol/kg wet weight) muscle glycogen contents, suggesting the supply of energy from glycogen utilisation cannot be replaced by an increased oxidation of blood glucose.' In set-distance events, high-carbohydrate diets have been reported to improve performance by 2 to 3% (abstract, PMID 9291549). 10.2165/00007256-199724020-00001
13. Romijn, J. A., Coyle, E. F., Sidossis, L. S., Gastaldelli, A., Horowitz, J. F., Endert, E., & Wolfe, R. R. (1993). Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration. American Journal of Physiology, 265(3 Pt 1), E380-E391. Stable isotope tracers and indirect calorimetry in five trained subjects at 25, 65 and 85% of maximal oxygen consumption. 'Plasma glucose tissue uptake and muscle glycogen oxidation increased in relation to exercise intensity. In contrast, peripheral lipolysis was stimulated maximally at the lowest exercise intensity, and fatty acid release into plasma decreased with increasing exercise intensity.' During 2 h at 65% of maximal oxygen consumption, oxidation of plasma-derived substrates rose over time while muscle glycogen and triglyceride oxidation fell. Conclusion: carbohydrate availability is regulated directly in relation to exercise intensity, while lipid regulation seems more complex (abstract, PMID 8214047). 10.1152/ajpendo.1993.265.3.E380
14. Nybo, L. (2003). CNS fatigue and prolonged exercise: effect of glucose supplementation. Medicine and Science in Sports and Exercise, 35(4), 589-594. Eight endurance-trained men did 3 h of cycling, randomized to be with or without glucose supplementation, and then a 2-min sustained maximal knee extension with twitch interpolation. Without glucose, blood glucose fell from 4.5 to 3.0 mM; with glucose it was maintained. Average force was 248 N at baseline, 222 N in the glucose trial and 197 N in the placebo trial, and in the placebo trial the lower force came with reduced central nervous system activation. Conclusion: 'Exercise-induced hypoglycemia attenuates CNS activation during a sustained maximal muscle contraction, whereas central activation appears to be unaffected by 3 h of moderately intense exercise in endurance-trained athletes when euglycemia is maintained by carbohydrate ingestion' (abstract, PMID 12673141). 10.1249/01.MSS.0000058433.85789.66
15. Smyth, B. (2021). How recreational marathon runners hit the wall: a large-scale data analysis of late-race pacing collapse in the marathon. PLOS ONE, 16(5), e0251513. Hitting the wall 'refers to the iconic hazard of the marathon distance, in which runners experience a significant slowing of pace late in the race, typically after the 20-mile mark, and usually because of a depletion of the body's energy stores.' Using pacing data from more than 4 million race records, a pacing-based definition (a sustained late-race slowdown) was used as a proxy: 28% of male and 17% of female runners hit the wall; when they did, males slowed more than females (relative slowdown 0.40 vs 0.37) and over longer distances (10.7 km vs 9.6 km), small effect sizes. Slowdowns were more frequent in the 3 years around a recent personal best (36% vs 23%) (abstract, PMID 34010308). 10.1371/journal.pone.0251513
16. Stellingwerff, T., & Cox, G. R. (2014). Systematic review: carbohydrate supplementation on exercise performance or capacity of varying durations. Applied Physiology, Nutrition, and Metabolism, 39(9), 998-1011. Sixty-one randomized, placebo (water-only) controlled performance studies (n = 679): 82% showed statistically significant performance benefits and 18% no change. There was a significant correlation between longer total exercise time and a larger percent performance gain with carbohydrate. In short exercise (about 1 h), oral exposure to carbohydrate stimulating reward centres of the brain provides a central mechanism, and 'the type and (or) amount of CHO and its ability to be absorbed and oxidized appear completely irrelevant'; in longer exercise (over 2 h), where muscle glycogen is stressed, the main mechanism is high rates of carbohydrate delivery and oxidation. Multiple transportable carbohydrates are beneficial in prolonged exercise, but recommendations should be tailored to each athlete's tolerance (abstract, PMID 24951297). 10.1139/apnm-2014-0027
17. Burke, L. M., Hawley, J. A., Wong, S. H., & Jeukendrup, A. E. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29(Suppl 1), S17-S27. Consensus review: carbohydrate availability is raised by eating carbohydrate in the hours or days before a session, during exercise and in recovery. 'Carbohydrate intake during exercise should be scaled according to the characteristics of the event. During sustained high-intensity sports lasting ~1 h, small amounts of carbohydrate, including even mouth-rinsing, enhance performance via central nervous system effects. While 30-60 g · h(-1) is an appropriate target for sports of longer duration, events >2.5 h may benefit from higher intakes of up to 90 g · h(-1). Products containing special blends of different carbohydrates may maximize absorption of carbohydrate at such high rates' (abstract, PMID 21660838). 10.1080/02640414.2011.585473
18. Coyle, E. F., Coggan, A. R., Hemmert, M. K., & Ivy, J. L. (1986). Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate. Journal of Applied Physiology, 61(1), 165-172. Seven endurance-trained cyclists exercised to fatigue at 71% of maximal oxygen consumption twice, once drinking a flavored-water placebo and once a glucose polymer solution. With placebo, fatigue came after 3.02 h and was preceded by a fall in plasma glucose to 2.5 mM; when fed carbohydrate, plasma glucose was maintained (4.2-5.2 mM) and they exercised for an additional hour (4.02 h). The pattern of muscle glycogen use did not differ over the first 3 h, and the extra hour was done with little reliance on muscle glycogen. Conclusion: when fed carbohydrate, highly trained endurance athletes can oxidize carbohydrate at relatively high rates from sources other than muscle glycogen late in prolonged strenuous exercise, 'and that this postpones fatigue' (abstract, PMID 3525502). 10.1152/jappl.1986.61.1.165
19. Jeukendrup, A. E. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), 452-457. Narrative review: the ceiling on exogenous carbohydrate oxidation sits in intestinal absorption, most likely saturation of carbohydrate transporters. Glucose alone had been taken as peaking near 1 g/min; combining carbohydrates that use different intestinal transporters (glucose plus fructose) raised measured exogenous oxidation to 1.75 g/min. The paper's own limit: this combination, ingested at high rates, is discussed for endurance work lasting 3 hours or more — not a universal feeding table. 10.1097/MCO.0b013e328339de9f
20. Costa, R. J. S., Miall, A., Khoo, A., Rauch, C., Snipe, R., Camões-Costa, V., & Gibson, P. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Applied Physiology, Nutrition, and Metabolism, 42(5), 547-557. Twenty-five endurance runners did a gut-challenge trial (2 h running at 60% of maximal oxygen uptake while taking 30 g carbohydrate gel-discs every 20 min, then a 1-h distance test), were randomly assigned to 2 weeks of repeated gut-challenge with carbohydrate gel-discs, carbohydrate food or placebo, and repeated the trial. Gastrointestinal symptoms fell by 60% with gel-discs and 63% with food, more than with placebo; the distance test improved by 5.2% and 4.3% but not with placebo (-2.1%); gel-discs also reduced malabsorption (breath hydrogen) and raised blood glucose; oxidation rates did not differ. Conclusion: 'Two weeks of gut-training with CHO-S and CHO-F improved gastrointestinal symptoms and running performance compared with PLA' (abstract, PMID 28177715). 10.1139/apnm-2016-0453
21. Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33. Review proposing guidelines scaled to the duration and intensity of exercise: 'during exercise lasting approximately 1 h in duration, a mouth rinse or small amounts of carbohydrate can result in a performance benefit. A single carbohydrate source can be oxidized at rates up to approximately 60 g/h and this is the recommendation for exercise that is more prolonged (2-3 h). For ultra-endurance events, the recommendation is higher at approximately 90 g/h.' At such high rates the carbohydrate must be multiple transportable carbohydrates to prevent accumulation in the intestine. The source may be liquid, semisolid or solid, and 'the recommendations may need to be adjusted downward when the absolute exercise intensity is low and thus carbohydrate oxidation rates are also low.' The advice is independent of body weight and training status. Author affiliation: Gatorade Sports Science Institute (abstract, PMID 24791914). 10.1007/s40279-014-0148-z
22. de Oliveira, E. P., Burini, R. C., & Jeukendrup, A. (2014). Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Medicine, 44(Suppl 1), S79-S85. Review: 'Generally, studies suggest that 30-50% of athletes experience such complaints. Most gastrointestinal symptoms during exercise are mild and of no risk to health, but hemorrhagic gastritis, hematochezia, and ischemic bowel can present serious medical challenges.' Causes are physiological, mechanical or nutritional; reduced mesenteric blood flow during intense exercise, especially when hypohydrated, is believed to be a main contributor. 'Nutritional training and appropriate nutrition choices can reduce the risk of gastrointestinal discomfort during exercise'; evidence for other proposed interventions is still lacking (abstract, PMID 24791919). 10.1007/s40279-014-0153-2
23. Sherman, W. M., Costill, D. L., Fink, W. J., & Miller, J. M. (1981). Effect of exercise-diet manipulation on muscle glycogen and its subsequent utilization during performance. International Journal of Sports Medicine, 2(2), 114-118. Three 6-day regimens in trained runners: classic low-then-high carbohydrate, mixed-then-high, and mixed throughout. Muscle glycogen on day 7 reached 207, 203, and 159 mmol glucosyl units/kg wet tissue. The 20.9 km performance run was not faster after the two high-glycogen regimens. The paper's own three conclusions: glycogen can be raised with a moderate exercise-diet regimen; starting glycogen changes how much is used; carbohydrate loading did not help this 20.9 km run. 10.1055/s-2008-1034594
24. Almond, C. S., et al. (2005). Hyponatremia among runners in the Boston Marathon. The New England Journal of Medicine, 352(15), 1550–1556. 2002 Boston Marathon: 766 enrolled, 488 gave a usable finish-line sample. Hyponatraemia (serum sodium <= 135 mmol/L) in 13%, critical (<= 120 mmol/L) in 0.6%. On multivariate analysis it was associated with weight gain (OR 4.2), racing time > 4:00 h (OR 7.4) and BMI extremes; female sex, the composition of fluids ingested (sports drink vs water) and NSAID use were not (abstract, PMID 15829535). 10.1056/NEJMoa043901
25. NHS. (2026). Heart palpitations. Heartbeat feels racing, irregular with skipped or extra beats, pounding or fluttering, in the chest, neck or throat; lasts seconds, minutes or longer; usually harmless. Common causes: strenuous exercise, lack of sleep, stress and anxiety, medicines, alcohol, caffeine, nicotine and recreational drugs; sometimes menopause or pregnancy; can be caused by iron deficiency anaemia, an overactive thyroid, an arrhythmia or other heart problems. See a GP if they keep coming back or happen more often, last longer than a few minutes, you have a heart condition, or there is a history of heart problems in your family. Call 999 or go to A&E if palpitations do not go away or come with chest pain, shortness of breath, feeling faint or fainting; if these symptoms have stopped, ask for an urgent GP appointment. Do not drive to A&E. Avoiding triggers such as stress, smoking, caffeine and alcohol can help when no condition is the cause; an ECG helps find the cause (page last reviewed 17 March 2026). www.nhs.uk/symptoms/heart-palpitations
26. Casa, D. J., DeMartini, J. K., Bergeron, M. F., Csillan, D., Eichner, E. R., Lopez, R. M., Ferrara, M. S., Miller, K. C., O'Connor, F., Sawka, M. N., & Yeargin, S. W. (2015). National Athletic Trainers' Association position statement: Exertional heat illnesses. Journal of Athletic Training, 50(9), 986-1000. 10.4085/1062-6050-50.9.07
27. Warden, S. J., Davis, I. S., & Fredericson, M. (2014). Management and prevention of bone stress injuries in long-distance runners. Journal of Orthopaedic & Sports Physical Therapy, 44(10), 749-765. Clinical commentary (level of evidence 5): 'Bone stress injury (BSI) represents the inability of bone to withstand repetitive loading, which results in structural fatigue and localized bone pain and tenderness. A BSI occurs along a pathology continuum that begins with a stress reaction, which can progress to a stress fracture and, ultimately, a complete bone fracture.' 'A BSI results from disruption of the homeostasis between microdamage formation and its removal'; the load applied to bone is the more modifiable side, through training-program design, reducing impact forces (running softer or with a higher stride rate) and strengthening local muscles such as the calf for tibial BSIs. Most BSIs heal after a period of modified loading and a progressive return to running, but they tend to recur (abstract, PMID 25103133). 10.2519/jospt.2014.5334
28. Riebe, D., Franklin, B. A., Thompson, P. D., Garber, C. E., Whitfield, G. P., Magal, M., & Pescatello, L. S. (2015). Updating ACSM's recommendations for exercise preparticipation health screening. Medicine & Science in Sports & Exercise, 47(11), 2473-2479. ACSM roundtable: 'there is considerable evidence that exercise is safe for most people and has many associated health and fitness benefits; exercise-related cardiovascular events are often preceded by warning signs/symptoms; and the cardiovascular risks associated with exercise lessen as individuals become more physically active/fit.' The new screening model rests on current activity level, the presence of signs or symptoms or known cardiovascular, metabolic or renal disease, and the desired exercise intensity (abstract, PMID 26473759). 10.1249/MSS.0000000000000664