With the hoopla surrounding Olympic lifting, plyometric training, and speed development, it’s rather easy to forget about the importance of developing endurance for your sport.
While establishing maximal strength and power development are integral pieces to your performance training puzzle, they won’t serve you well if you cannot sustain your performance throughout competition.
Muscular endurance is the ability of muscle or a muscle group to produce and maintain a given force or power output for a prolonged duration. With the exception of pure power sports, such as Olympic lifting and field events, such as throwing and jumping, varying degrees of muscular endurance are vital to athletic performance.
Examples of such include:
· A running back who carries the ball 30 times per game
· Boxers and mixed martial artists who progress in to the later rounds of a bout
· A major league starting pitcher, who may throw between 90 and 120 pitches per contest
· Ice hockey players who often go all out during 30 to 60 second shifts repeatedly throughout the game
For instance, a running back who is capable of running a 4.35 second 40 yard dash, but lacks muscular endurance, may be running at 4.8 or 4.9 speed at five or six carries into the game. Likewise a pitcher who’s fastball tops out at 90 miles per hour, but lacks muscular endurance, might be hurling with far less ched, a few batters into their outing.
While addressing muscular endurance is imperative, we must first have a cursory understanding of the mechanisms at play that induce fatigue.
Every movement is initiated at the cellular level and is fueled by the body’s production of ATP – your body’s energy currency. Setting the stage for movement, are muscular contractions, which involve a cascade of cellular activity. First, ATP is split, forming a high energy myosin-ATP cross bridge which attaches to actin and releases potential energy contained within its bonds. Second, the cross bridge pulls actin toward the center of the sarcomere. Next, ATP binds to the cross bridge from actin to begin contracting. Two proteins which inhibit the binding of myosin and actin are blocked by calcium, which is activated by the depolarization of a motor neuron and subsequent action potential which envelops the surface of the muscle fiber and enters it through the transverse tubules and spreads over the sarcoplasm.
If ATP cannot be produced quickly enough and split to form myosin-ATP cross bridges, power output of the muscle will be reduced. Initially, ATP is primarily generated via anaerobic pathways – conversion of phospates and glycogen. Eventually, as the duration of the output continues, there becomes a greater dependency on aerobic pathways for ATP production.
Now what exactly causes fatigue?
Insufficient Energy Substrates
Energy that is produced anaerobically utilizes intracellular glycogen stores and circulating blood glucose. Glycogen and glucose are used to form pyruvate, which is converted to acetyl coenzyme A, which enters the mitochondria for oxidation, which triggers the production of more ATP.
When oxygen cannot be supplied quickly enough the meet the demands of muscular activity due to a lack of available glycogen, hydrogen ions accumulate, interfering with the interaction and consequent force production of cross bridges as well as disrupting the functioning of the sarcoplasmic reticulum.
Reduced Neural Activation
If motor neurons cannot be activated repeatedly by the nervous system, then depolarization cannot transpire, thus impeding the release of calcium, permitting inhibitory proteins to block the interaction of myosin and actin in turn decreasing force output.
Lack of Oxygenated Blood
Often overlooked is the role of an athlete’s cardiorespiratory fitness level, which in conjunction with foundational qualities as strength, enable the enhancement and display of athleticism. Intense activities conducted near one’s VO2Max, or maximal aerobic capacity, require a proportional cardiac output to supply those working muscles with oxygenated blood. If oxygenated blood cannot be supplied quickly enough to working muscles, fatigue and reduced force output will result. Also, a robust cardiorespiratory fitness level will permit a quicker recovery between high intensity outputs.
Strategies can be instituted throughout the year to ensure that activity specific endurance is established and maintained.
· During the early stages of offseason training, work capacity should be built through general physical preparedness activities, which include resistance training
· Progressive overload should be utilized with regards to building volume each workout and each training week via sets, reps, and density progression
· Cardiorespiratory fitness training should never be neglected, regardless of the sport, event, or level of competition the athlete participates in
· As the competitive season nears, the physiological work performed should begin to resemble the demands of competition (i.e. work to rest ratios should begin to approach the intervals and tempo at which the game is played at)
· Exercises which require immense technical proficiency such as Olympic lifts should not be used for conditioning
· Plyometric exercises, which incur great neural demands and orthopedic stresses should not be performed to fatigue
· Physical activity, namely cardiorespiratory fitness training, should be performed with fluctuating intensities and durations throughout the offseason
· The demands of the sport should dictate the proportion of strength training and cardiorespiratory fitness training performed during the year
· Be sure to fuel yourself properly prior to, during, and following practice, training, and competition
· Remember, specificity reigns supreme – you get what you train for or don’t train for. If you’re ignoring conditioning, you can expect to be out of shape when your season begins or on your competition.