title: Physiological, biochemical and functional changes induced by a simulated 30 min off-road competitive motocross heat.
abstract: OBJECTIVE
  Up to now, few studies regarding the impact of motocross heats on functional and physiological variables have been addressed so far. The aim of the present study was to analyze physiological and functional changes induced by a simulated off-road motocross heat.
  
  
  METHODS
  Fifteen motocross riders (28.3+/-7.9 yrs; 71.1+/-7.0 kg; 169.0+/-4.0 cm; 53.5+/-3.7 mL.kg(-1).min(-1); 14.9+/-3.3% fat) performed one treadmill running to exhaustion to determine maximal heart rate (HRmax) and maximal oxygen consumption. Thereafter, simulated 30 min competitive off-road motocross heats were performed to measure biochemical (blood lactate and urine catecholamine concentrations) and functional (upper-limb power and fatigue--Wingate and Handgrip) alterations induced by the race. Exercise intensity through HR monitoring, rating of perceived exertion and upper-limb pain were also accomplished.
  
  
  RESULTS
  During the 30 min heats, the riders spent 87% of time above 90% of their HRmax. Significant impairments were observed on maximal isometric handgrip as well as on Wingate variables after the race. Blood lactate concentrations significantly increased from rest vs 10 min, 20 min and final time of analysis (P < 0.05). However, a significant decrease was observed between 10 min vs 20 min and final of the race. A significant increase in the 24-h urine catecholamine levels was observed after the race.
  
  
  CONCLUSIONS
  The present data suggest that motocross heats are performed at high exercise intensity. Motocross specific effort induces significant functional alterations that may reflect muscle fatigue with consequent decrement on physical performance.
authors.affiliation: Research Centre in Physical Activity, Health and Leisure, University of Porto, Porto, Portugal. aascensao@fcdef.up.pt
authors.forename: A
authors.initials: A
authors.lastname: Ascensão
authors.forename: V
authors.initials: V
authors.lastname: Azevedo
authors.forename: R
authors.initials: R
authors.lastname: Ferreira
authors.forename: E
authors.initials: E
authors.lastname: Oliveira
authors.forename: F
authors.initials: F
authors.lastname: Marques
authors.forename: J
authors.initials: J
authors.lastname: Magalhães
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000886:Anthropometry; D003163:Competitive Behavior; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D018737:Hand Strength / Q000502:physiology*; D006339:Heart Rate; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D009049:Motorcycles; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D010865:Pilot Projects; D013997:Time Factors; D055815:Young Adult