EXPH 2115 Key Terms - Lecture 4: Energy Expenditure

graded-intensity exercise

protocol in which the workload increases in a progressive fashion (e.g., treadmill stress test)

stress test (aka GXT, CPX)

progressively increasing workload protocol with the goal of subject attempting maximal aerobic effort

VO₂max

maximal capacity to consume O₂, indicative of cardiorespiratory fitness when expressed in mL/kg*min

Absolute VO₂max

highest achievable VO₂ expressed in L/min (e.g. 3 L/min), correlates with body size and training

Relative VO₂max

a body mass-specific expression of VO₂max (e.g. 45 mL/kg*min), indicator of aerobic fitness

cardiorespiratory fitness

term for relative VO₂max (i.e. aerobic capacity), can be an indicator of health or athletic potential

VO₂max testing primary criterion

a plateau in VO₂ with an increase in power (defined as less than a 150 mL/min increase between stages)

VO₂max testing secondary criteria

HRmax ± 10 bpm of age-predicted HRmax, RER > 1.10, RPE > 18, lactate > 8.8 mmol/L (in combination)

VO₂peak

highest VO₂ recorded during a GXT not deemed maximal (numerous reasons for not reaching VO₂max)

Hematocrit

fraction of blood sample occupied by RBCs, commonly 40% and 45% in females and males, respectively

physiological peak

point (~30 yr) when a variety of physiological/performance parameters (e.g. VO₂max) decreases with aging

constant-load exercise

protocol in which workload is not changed during the course of the bout, steady state achieved

oxygen deficit

inadequate aerobic metabolism at start of exercise, anaerobic sources contribute to meet ATP demands

steady state VO₂

period when ATP needs are being met by aerobic metabolism without lactate accumulation, constant VO₂

excess post-exercise VO₂ (EPOC)

O₂ consumption elevated above resting levels after exercise, degree of which correlates with exercise dose

absolute exercise intensity

workload expression free of individual capacities (e.g. 50 watts of power, 1.5 L/min VO₂, 7 mph velocity)

relative exercise intensity

workload expression relative to an individual’s maximal capacity (e.g. %VO₂max, % of max power)

low (light) exercise intensity

35-50% VO₂max (various paces of walking)

moderate exercise intensity

50-65% VO₂max (brisk walking to light, conversational-pace jogging)

high (heavy) exercise intensity

65-80% VO₂max (jogging to running)

mixed diet

diet with standard combination of energy nutrients represented (e.g.50% CHO, 35% fat, 15% protein)

low vs high carbohydrate diet

diets representing extremes in CHO intake (e.g. < 20% vs > 60%)

onset of blood lactate accumulation

OBLA is point during GXT when lactate production outpaces clearance (aka anaerobic/lactate threshold)

anaerobic/lactate threshold

GXT intensity when blood lactate rises exponentially, below which exercise can be significantly sustained

exercise economy

VO₂ (energy requirement) for a given workload — the lower the VO₂, the greater the economy

mechanical efficiency

percentage of energy expended that appears as external work

biomechanical skill

ability of the neuromuscular unit to precisely and efficiently coordinate complex movements

glycogen depletion

reduction in intramuscular glycogen stores thus contributing to fatigue

fatigue

acute and reversible inability to maintain a desired force output without increased effort