SMARTER ATHLETES Understanding muscular systems

What are we talking about? In a strength and conditioning environment, selfsufficient athletes with a purposeful training routine understand how different exercises and movement patterns influence different training systems. Today we are differentiating between muscular endurance, strength, and power as benefits of conditioning, and specifically, how we approach a workout and/or exercises in order to target a desired result.

Why are we talking about it? Athletes that are targeting improvement in a specific area of fitness/conditioning benefit from selecting appropriate exercises and drills during program design. Set, repetition, loading, and rest protocols can also influence training stimuli and adaptations. When program design and re-design align with specific goals and targets set by athletes and coaches, transition to improved sport-specific performance is likely.

Part One. Muscular Endurance Part Two. Muscular Strength Part Three. Muscular Power Part Four. Application & Assessment

Part One. Muscular Endurance

Muscular Endurance Refers to the ability of muscle or a group of muscles to sustain repetitive stress and continuous contractions against resistance before the onset of fatigue. Muscular endurance is dependent on: Type I (slow-twitch) Fibres Percentage and rate of activation. Influences of Oxygen Delivery Stroke volume, VO2 MAX, onset of blood lactate accumulation (OBLA).

Slow Twitch (Type I) Fibres Type one fibres are most efficient in using oxygen-rich blood for continuous contractions for extended periods of time. These fibres typically fire more slowly than their fast-twitch (type II) counterparts. Higher concentrations of slow twitch fibres are ideal for endurance athletes, but a combination of muscular endurance and muscular strength/power is often ideal for any athletes who repetitively stress specific joints through continuous skilled movement.

Influences on O2 Delivery Stroke Volume The volume of oxygen-rich blood that can be delivered per heart beat. V02 Max An athletes maximal rate of oxygen consumption during exercise. Onset of Blood Lactate Accumulation (OBLA) The level of intensity at which blood lactate (by-product of fast glycolysis) begins to build.

Muscular Endurance 1. Tolerance for repetitive stress 2. Reduced likelihood of chronic injury 3. Delay the onset of muscular fatigue 4. Withstand higher volumes of training 5. Withstand higher frequency of training 6. Build a foundation for strength and power

Muscular Strength

Part Two. Muscular Strength

Muscular Strength Refers to the maximal amount of force that can be exerted against resistance from an object or oppositional force and is ultimately determined by two factors: Cross Sectional Area of Muscle (CSA) Muscular size and thus, amount of muscle fibre. Intensity of Recruitment The percentage of muscle fibres activated and their output capabilities.

Cross-sectional Area of Muscle Cross-sectional area (size) of muscle limits the total number of muscle fibre bundles (fascicles) that can operate collectively when a muscle is exerting force. At the cellular level, muscular growth in response to resistance training (hypertrophy) is dependent on hormonal activity and adaptations. Testosterone, growth hormone, cortisol, and insulin-like growth factor (IGF) all play a role in adaptations to resistance training, and are elevated during stages of maturation/puberty and peak rates of growth.

Intensity of Recruitment Recruitment of muscle or motor unit recruitment refers to the process of muscle activation. A motor unit refers to one neuron and muscle fibres that are activated by it. The number of muscle fibres that belong to a motor unit can vary significantly depending on the muscle. Recruitment is the term used to refer to the theoretical number or percentage of neurons that become active in a muscle during a task that requires contractile strength.

Muscular Strength 1. Increase force production 2. Increase cross-sectional area of muscle 3. Increase amount of available motor units 4. Tolerate higher resistance loads / forces 5. Improve low-speed resisted movement

Part Three. Muscular Power

Muscular Power Refers to the rate at which muscle can be utilized to move against resistance. As a trainable system, muscular power relies on rapid force development through speed of movement and the amount of fast-twitch muscle available. Speed of movement Appropriate resistance loads for training rapid force development must be sub-maximal in order to encourage a higher speed of movement. Type II (fast-twitch) Fibres Percentage and rate of activation.

Speed of Movement Muscular power is not simply a measure of force production alone. It refers to a rate of force production, and thus, speed of muscular recruitment. In order to truly train muscular power, an athlete must first improve muscular strength, and then improve the speed of force production through high-speed movement in a training environment. In untrained individuals, lower-speed maximal strength exercises can improve muscular power on their own, but only to a certain extent.

Fast Twitch Muscle Fast twitch (Type II) muscle fibres are responsible for quick and powerful contractions. They fatigue rapidly, and can only contribute to short, anaerobic efforts before an athlete will experience significant diminishing returns in successive efforts along with pain or soreness. Type II fibres also have the greatest potential for increase in mass.

Muscular Power 1. Improve high-speed movement potential 2. Increase recruitment of available motor units 3. Improve coordinative ability in high sp. workload 4. Enhance speed/efficiency in stretch-shorten cycle 5. Improve performance in low-speed resisted movement

Part Four. Application & Assessment

Application SYSTEM SET REP %1RM REST INTVL MUSCULAR ENDURANCE 2-3 12+ < 60 < 60s HYPERTROPHY 3-4 8-10 70-80 2m STRENGTH 4-5 3-5 > 85 3-4m POWER 4-6 2-4 > 85 3-4m PEAK POWER 3-4 2-3 75-80 3-4m Source: Baechle, T. & Earle, R. Essentials of Strength Training and Conditioning: 3rd Edition. National Strength & Conditioning Association. Human Kinetics Publishers. 2008

Guidelines for Assessment WARNING: Using tests of muscular strength that are mechanically dissimilar to the performance of interest can compromise the external and predictive validity of the data gathered Self-selection of metrics for improved strength and power should reflect sport-specific movement whenever possible.

Sources of Info Michael S. Conley, Ph.D., CSCS and Michael H. Stone, Ph.D., CSCS. Explosive Exercise. Published by The American College of Sports Medicine McCloud, Aaron (30 November 2011). "Build Fast Twitch Muscle Fibers". Complete Strength Training. Retrieved 30 November 2011. Ounjian, M., R.R. Roy, E. Eldred, A Garfinkel, J.R. Payne, A. Armstrong, A. Toga, and V.R. Edgerton Physiological and Developmental Implications of Motor Unit Anatomy. J. Neurobiol. 22:547-559, 1991. Motor unit territory. Methods of Measurement for Muscular Strength. NSCA s Guide to Tests and Assessment. 2008 www.nsca-lift.org Baechle, T. & Earle, R. Essentials of Strength Training and Conditioning: 3rd Edition. National Strength & Conditioning Association. Human Kinetics Publishers. 2008 Marieb, EN; Hoehn, Katja (2010). Human Anatomy & Physiology (8th ed.). San Francisco: Benjamin Cummings. p. 312.

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