Physiology of Resistance Training

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Questions and Answers

What is the dominant mechanism for training-induced increases in muscle mass?

Hyperplasia

Decreased fat infiltration

Increased muscle proteins (correct)

Increased neural drive

Which physiological variable shows a small shift from type 2x to 2a fibres?

Muscle fibre type (correct)

Bone mineral content

Nervous system

Muscle mass

What physiological effect has unclear outcomes related to muscle training?

Muscle oxidative capacity (correct)

Muscle antioxidant capacity

Tendon and ligament strength

Muscle mass

Increased antioxidant capacity following resistance training shows what level of increase?

Almost 100% Signup and view all the answers

What adaptation can be observed rapidly after the initiation of a training program?

Increased neural drive Signup and view all the answers

What is the tallest possible effect on tendon and ligament strength due to resistance training?

Increased strength Signup and view all the answers

Which type of muscle fibers has been shown to produce increased specific force?

Type 1 fibers Signup and view all the answers

Which outcome is associated with resistance training regarding muscle mass?

Hypertrophy detectable within 3 weeks Signup and view all the answers

What is a potential disadvantage of using isolated muscles to study fatigue mechanisms?

It may introduce bias from extracellular gradients. Signup and view all the answers

What aspect of central fatigue is suggested if the CNS is impaired?

Reduced number of functioning muscles involved in activity. Signup and view all the answers

How does encouragement affect fatigue levels according to recent studies?

It can lead to improved performance and surpassing previous maximums. Signup and view all the answers

Which neurotransmitter's levels have been studied in relation to fatigue?

Serotonin and epinephrine. Signup and view all the answers

What is one indication of central fatigue?

Depression of stimulatory drive. Signup and view all the answers

What does peripheral fatigue primarily depend on?

Metabolite accumulation in muscles. Signup and view all the answers

What is a characteristic finding when studying fatigue in vivo versus isolated fibers?

Isolated fibers exhibit more consistent fatigue patterns. Signup and view all the answers

What can an increase in serotonin levels indicate in terms of fatigue?

Potential contribution to fatigue. Signup and view all the answers

How quickly are mitochondrial adaptations lost with detraining?

50% lost within the first week Signup and view all the answers

What is the primary fuel source for exercise lasting less than 10 seconds?

ATP-PC system Signup and view all the answers

What adaptation occurs with anaerobic training greater than 30 seconds?

Mitochondrial biogenesis Signup and view all the answers

What does W prime represent in the context of exercise physiology?

Anaerobic capacity Signup and view all the answers

Which method is recommended for identifying the lactate threshold?

Incremental exercise test with steps Signup and view all the answers

How long does it generally take for peak anaerobic capacity to increase by 3-25% through anaerobic training?

4-10 weeks Signup and view all the answers

What is the primary focus of measuring critical power (CP) in exercise?

Establishing maximal aerobic power Signup and view all the answers

What effect does endurance exercise training have on the cardiovascular (CV) control center during submaximal exercise?

Reduces feed forward output from higher brain centers Signup and view all the answers

What is the outcome of improved muscle homeostasis due to training?

Reduced feedback to the CV control center Signup and view all the answers

What is the significance of the point of change in the v-slope method while assessing anaerobic threshold?

It marks the transition to anaerobic metabolism Signup and view all the answers

How is W prime related to critical power (CP)?

W prime is the energy available above CP. Signup and view all the answers

Which adaptation is associated with anaerobic training?

Elevated enzymes involved in glycolysis Signup and view all the answers

What is the role of intramuscular phosphocreatine (PCr) in the context of W prime?

It regulates mitochondrial respiration. Signup and view all the answers

What is the significance of optimizing athlete training?

Athletes spend more time training than competing Signup and view all the answers

What does the Dmax method aim to indicate during a lactate threshold test?

Inflection point of lactate concentration Signup and view all the answers

Which testing protocol is preferable for accurately determining both anaerobic threshold and critical power?

Multiple time trials with varied durations Signup and view all the answers

What is the relationship between muscle atrophy and prolonged inactivity?

20-30 days of inactivity can cause a 20-30% reduction in muscle fiber size. Signup and view all the answers

Which factor has the greatest influence on VO2max differences among individuals?

Stroke volume Signup and view all the answers

How can VO2max be increased effectively?

Training large muscle groups at least 3 times per week above 50% VO2max. Signup and view all the answers

What is primarily retained during a period of detraining that contributes to faster strength recovery?

Myonuclei in trained fibers Signup and view all the answers

What happens to stroke volume with changes in preload and afterload?

Preload increases and afterload decreases, enhancing stroke volume. Signup and view all the answers

What is a common misconception about muscle memory during retraining?

Rapid gains occur solely because of previous training experience. Signup and view all the answers

What role does protein synthesis play in maintaining muscle mass?

It needs to be balanced with muscle protein breakdown to conserve mass. Signup and view all the answers

How does the body respond to increases in VO2max over time?

Short-duration adaptations are primarily from increased stroke volume. Signup and view all the answers

Study Notes

Training Induced Increases in Muscle Mass

Hyperplasia - increase in muscle fibre number, limited evidence in humans.
Hypertrophy - increase in muscle fibre cross sectional area, dominant factor in resistance training.

Physiological Variables Affected By Resistance Training

Nervous System - increased neural drive, potential changes in agonist/antagonist activation ratio.
Muscle Mass - increased.
Muscle Fibre Specific Force Production - increased in type 1 fibres only.
Muscle Fibre Type - small shift from type 2x to 2a fibres.
Muscle Oxidative Capacity - unclear, depends on type of resistance training.
Muscle Capillary Density - unclear, depends on type of training.
Muscle Antioxidant Capacity - increased, 12 weeks of training increases antioxidant enzyme activity by almost 100%.
Tendons And Ligament Strength - increased.
Bone Mineral Content - increased, resulting in stronger bones.

Muscle Fatigue

Fatigue is a complex process with multiple contributing factors.
Peripheral Fatigue - accumulation of metabolites and depletion of energy stores in muscle.
Central Fatigue - fatigue of the CNS.

Central Fatigue

May lead to reduction in number of motor units and firing frequency.
Research supports and contradicts CNS role in fatigue.
Mental state and motivation can influence performance.
Impairment of voluntary muscle contraction may stem from CNS issues.
Overtraining (OT) can contribute to fatigue.

Critical Power (CP)

Highest exercise intensity sustainable for prolonged periods.
Synonymous with anaerobic, lactate and ventilatory threshold.
Determined through time trials, not measuring VO2 or lactate.
Requires curve fitting and mathematical analysis.
W above critical power is W prime, representing anaerobic capacity.
Asymptote of fitted curve represents CP.
Tested through multiple time trials of varying durations (12-20 minutes).

Lactate Threshold (LT)

Inflection point in lactate exercise intensity relationship.
Beginning of non-linear increase in lactate concentration.
Identified by a sudden increase in lactate on a graph.
Measured using incremental exercise tests with blood samples.
Requires careful data analysis method selection.

Anaerobic Threshold

Determines maximum sustainable aerobic power.
Older method compared to CP and LT2.
Predictive of performance, potentially more useful than VO2max.
Reflected by a change in the relationship between ventilation and oxygen consumption.
Also known as the first ventilatory threshold (VT1).
Identified using the V-Slope method on a graph.

Detraining Following Strength Training

Ceasing resistance training leads to atrophy and strength loss.
Strength losses occur slower than endurance based adaptations.
Strength loss can be recovered quickly with resumed training.

Muscle Memory

Controversial concept.
Research suggests it is due to resistance training induced myonuclei.
Myonuclei are not lost during detraining, providing an advantage for protein synthesis upon retraining.

Prolonged Inactivity and Muscle Atrophy

20-30 days of inactivity leads to 20-30% reduction in muscle fibre size.
Conservation of muscle mass relies on balance between MPS and MPB.
Increased radial production promotes muscle atrophy.

Training and Changes in VO2max

VO2max represents the body's maximum oxygen transport and utilization during dynamic exercise.
Determined by the Fick Equation: VO2max = Max Cardiac Output x a-vO2 difference.
Primary difference in VO2max between people is stroke volume.

Training To Increase VO2max

Large muscle group training.
Endurance based activity 3+ times per week, above 50% VO2max.
HIIT can also increase VO2max.

Responses to Increases in VO2max

15-20% increase in general population.
Smaller increases in individuals with already high VO2max.
Up to 50% increase in individuals with very low VO2max.
Short duration adaptations likely due to increased volume.
Long duration responses due to changes in stroke volume and a-vO2 differences.

Factors Influencing Stroke Volume

TPR (afterload), contractility and EDV (preload).
EDV is influenced by plasma volume, filling time, venous return and ventricular volume.
Preload increases, afterload decreases with training.
Detraining leads to rapid loss of mitochondrial adaptations.

Muscle Adaptations to Anaerobic Exercise

Anaerobic training intensities are above VO2max.
Fuelled primarily by ATP-PC and glycolysis systems.
10-30 second effort, recruits type 1 and 2 fibres.
Less than 10 seconds fueled by ATP-PC system.
20-30 seconds effort, 80% anaerobic energy, 20% aerobic.
Adaptations include: better buffering capacity, hypertrophy of type 2 fibres, elevated enzymes for ATP-PC and glycolysis.
HIIT above 30 seconds promotes mitochondrial biogenesis.

Training - Muscle and Systemic Physiology

Biochemical adaptations to training influence physiological responses.
Peripheral feedback from muscle to CNS: training improves muscle homeostasis, reducing feedback from muscle chemoreceptors to the CV control centre.
Central control of physiological response: endurance exercise training reduces feedforward output from higher brain centres to the CV control centre during submaximal exercise.

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Description

This quiz covers the physiological adaptations induced by resistance training, focusing on muscle mass changes, neural drive, and various muscle fiber characteristics. It also discusses the impact of training on muscle oxidative capacity, capillary density, and overall strength. Test your knowledge on these important concepts!