Table 2.

Summary of the effects of warm-up (WU) on physiological parameters based on a systematic search of the published literature.

Study [Citation]	Study Design	Warm-Up and Studied Parameters	Main Results on the Effects of Warm-Up
Aerobic metabolism
Lund, 1996 [34]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 TB Intervention: high-intensity exercise (105% VO2max) on treadmill	Warm-up regimens: Low-intensity: 5 min walk, 400 m canter, 5 min walk High-intensity: 5 min trot, canter until venous temperature > 39.5 °C, 5 min trot Parameters: VO2, HR, cardiac output, blood lactate	Low-intensity WU had beneficial effect on VO2 WU lowered peak plasma lactate concentration and its subsequent disappearance
Tyler, 1996 [35]	Design: randomized crossover, without versus with WU Subjects: 13 SB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimen: 5 min trot at 50% VO2max Parameters: VO2, VCO2, total run time to fatigue, blood lactate	WU accelerated kinetics of gas exchange WU increased proportion of total energy requirement supplied by aerobic sources
McCutcheon, 1999 [36]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 SB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Low-intensity: 10 min at 50% VO2max High-intensity: 5 min at 50% VO2max followed by 45 s intervals at 80, 90, and 100% VO2max Parameters: VO2, total run time to fatigue, middle gluteal muscle biopsies, hematocrit, plasma total protein, blood lactate	WU was associated with higher aerobic energy contribution to total energy expenditure, lower glycogenolysis, and longer run time to fatigue WU decreased rate of blood and muscle lactate accumulation No additional benefit of high- versus low-intensity
Geor, 2000 [37]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 SB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Low-intensity: 10 min at 50% VO2max High-intensity: 7 min at 50% VO2max followed by 45 s intervals at 80, 90, and 100% VO2max Parameters: VO2, VCO2, CO2	WU accelerated VO2 and VCO2 kinetics WU decreased accumulated O2 deficit
Mukai, 2008 [38]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 11 TB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Moderate-intensity: 1 min at 70% VO2max High-intensity: 1 min at 115% VO2max Parameters: VO2, VCO2, total run time to fatigue, blood lactate	WU increased VO2 peak values and decreased blood lactate accumulation during the first minute of intense exercise (suggesting greater aerobic than net anaerobic power) Higher time to fatigue following moderate-intensity WU
Mukai, 2010 [39]	Design: randomized crossover, with 3 different WU regimens Subjects: 9 TB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens (canter): Low-intensity: 400 s at 30% VO2max Moderate-intensity: 200 s at 60% VO2max High-intensity: 120 s at 100% VO2max Parameters: VO2, VCO2, CO2, HR, blood lactate	High-intensity WU accelerated VO2 kinetics High-intensity WU reduced reliance on net anaerobic power compared to low-intensity WU
Farinelli, 2021 [40]	Design: randomized crossover, without versus with WU Subjects: 6 MM horses Intervention: 50 min Marcha test	Warm-up regimen: 10 min walking at 10 km/h Parameters: HR, RR, blood lactate and glucose, CK, AST, serum cortisol	WU was not associated with changes in HR, RR, lactate, glucose, CK, AST, or cortisol directly after this predominantly aerobic intervention Faster HR recovery when horses performed WU
Thermoregulation
Lund, 1996 [34]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 TB Intervention: high-intensity exercise (105% VO2max) on treadmill	Warm-up regimens: Low-intensity: 5 min walk, 400 m canter, 5 min walk High-intensity: 5 min trot, canter until venous temperature > 39.5 °C, 5 min trot Parameters: heat loss from airways, heat storage	Low-intensity WU had beneficial effect on heat balance (accumulation of heat was slower, despite higher body temperature at onset of maximal exercise) Low-intensity WU initiated sweating and promoted better thermoregulation
McCutcheon, 1999 [36]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 SB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Low-intensity: 10 min at 50% VO2max High-intensity: 5 min at 50% VO2max followed by 45 s intervals at 80, 90, and 100% VO2max Parameters: blood (right atrium) and middle gluteal muscle temperatures	WU increased muscle temperature No additional benefit from high- versus low-intensity
Geor, 2000 [37]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 6 SB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Low-intensity: 10 min at 50% VO2max High-intensity: 7 min at 50% VO2max followed by 45 s intervals at 80, 90, and 100% VO2max Parameters: blood temperature	Blood temperature increased after WU which was maintained throughout the exercise Increase in blood temperature depended on WU intensity: ○Low-intensity: by 0.9 ± 0.1 °C after WU ○High-intensity: by 1.9 ± 0.2 °C after WU
Mukai, 2008 [38]	Design: randomized crossover, without versus with 2 different WU regimens Subjects: 11 TB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens: Moderate-intensity: 1 min at 70% VO2max High-intensity: 1 min at 115% VO2max Parameters: blood temperature (pulmonary artery)	WU exercise induced an increase in blood temperature, which was maintained throughout the whole sprint
Mukai, 2010 [39]	Design: randomized crossover, with 3 different WU regimens Subjects: 9 TB Intervention: high-intensity exercise (115% VO2max) on treadmill	Warm-up regimens (canter): Low-intensity: 400 s at 30% VO2max Moderate-intensity: 200 s at 60% VO2max High-intensity: 120 s at 100% VO2max Parameters: blood temperature (pulmonary artery)	All WU regimens increased blood temperature Blood temperature during sprint was higher following high-intensity than low- and moderate-intensity WU
Buchner, 2017 [41]	Design: randomized crossover, without versus with 3 different WU regimens Subjects: 10 horses Intervention: examination before and after WU	Warm-up regimens: Regimen 1: 10 min whole-body vibration Regimen 2: 10 min extended walk Regimen 3: 8 min extended walk and 2 min trot Parameters: core and skin temperature, HR, RR	No difference in HR and core temperature after any WU regimens compared to no WU Slight increase in RR after walk and trot WU No difference in skin temperature after whole-body vibration Small increases in skin temperature after walk, and walk/trot WU
Janczarek, 2021 [42]	Design: randomized crossover, with 4 different WU regimens Subjects: 12 Warmblood horses Intervention: WU regimens of different durations in sand outdoor arena	Warm-up regimens: Very short: 10 min walk, 5 min trot, 5 min walk Short: 10 min walk, 10 min trot, 5 min walk Extended: 10 min walk, 15 min trot, 5 min walk Long-lasting: 10 min walk, 20 min trot, 5 min walk Parameters: body and mid-cannon surface temperature	WU increased body and surface temperatures, proportionally to its duration WU effect was achieved earlier and lasted longer in heavily trained horses than in non-performance horses
Farinelli, 2021 [40]	Design: randomized crossover, without versus with WU Subjects: 6 MM horses Intervention: 50 min Marcha test	Warm-up regimen: 10 min walking at 10 km/h Parameters: rectal temperature	WU increased rectal temperature before the Marcha test
Acid-base balance and biochemistry
Frey, 1995 [43]	Design: randomized crossover, without versus after administration of sodium carbonate Subjects: 12 SB Intervention: race on track	Warm-up regimens: 2-mile slow or 1-mile fast Parameters: blood pH, HCO3−, PCO2, base excess, Na+, Ca++, Cl−, K+	Decreased PCO2, base excess and Ca++ after WU Increased K+ after WU
Fazio, 2012 [44]	Design: prospective observational Subjects: 10 healthy Italian saddle horses Intervention: WU and simulated show jumping competition	Warm-up regimen: 15 min (pacing, trotting, galloping, and 6 jumps 1.00–1.40 m) Parameters: Hematology and biochemical: lactate, bicarbonate, HCO3−, TCO2, O2 capacity and content, base excess of blood and extracellular fluid, pH, PCO2, PO2, SO2, hematocrit, and hemoglobin HR	Increased HR, lactate, TCO2, O2 capacity and content, base excess of blood and extracellular fluid, PCO2, PO2, SO2, hematocrit and hemoglobin after WU No difference in HCO3− or pH after WU
Fazio, 2014 [45]	Design: prospective observational Subjects: 7 healthy Italian saddle horses Intervention: WU and simulated show jumping competition	Warm-up regimen: 15 min (pacing, trotting, galloping, and 6 jumps 1.20–1.40 m) Parameters: Serum: ALP, ALT, AST, CK, GGT, LDH, creatinine, urea, total bilirubin, glucose, Na+, Cl−, K+ HR and blood lactate	Increased HR, lactate, ALT, AST, CK, creatinine and K+ after WU Decreased glucose concentration after WU No difference in ALP, GGT, LDH, urea, total bilirubin, Na+ or Cl− after WU

ALP: alkaline phosphatase; ALT: alanine transaminase; AST: aspartate transaminase; CK: creatine kinase; CO₂: carbon dioxide; GGT: gamma-glutamyltransferase; HCO₃⁻: bicarbonate; HR: heart rate; LDH: lactate dehydrogenase; MM: Mangalarga Marchador; O₂: oxygen; PCO₂: partial pressure of carbon dioxide; PO₂: partial pressure of oxygen; RCT: randomized clinical trial; RR: respiratory rate; SB: Standardbred; SO₂: oxygen saturation; TB: Thoroughbred; TCO₂: total carbon dioxide; VO₂: oxygen consumption or aerobic capacity; VO_2max: maximal oxygen consumption or aerobic capacity; VCO₂: rate of elimination of carbon dioxide.