Preventing injury to the athlete is on of the primary functions of the athletic trainer. To compete successfully at a high level, the athlete must be fit. An athlete who is not fit is more likely to sustain an injury. Both coaches and athletic trainers recognize that improper coaching is one of the major causes of sports injuries.
Sports conditioning often falls into three seasons:
Periodization is an approach to conditioning that brings about peak performance while reducing injuries and over-training in the athlete through a training and conditioning program that is followed throughout the various seasons. Periodization takes into account that athletes have different needs relative to training and conditioning during different seasons and modifies the program according to individual needs.
Off-season Transition period
Hypertrophy period (cross training)
Low intensity, high volume, non-sport specific
Moderate intensity, moderate volume, more sport specific
Pre-season Power phase
High intensity, decreased volume, sport specific
In-season Competition period
High intensity, low volume, skill-training, strategic
PRINCIPLES OF CONDITIONING
The following principles should be applied in all programs and conditioning to minimize the likelihood of injury:
2. Motivation. Athletes are generally motivated to work hard because they want to be successful in their sport.
3. Overload. To see improvement in any physiological component, the system must work harder than it is accustomed to working. LOGAN AND WALLS identified the SAID principle, which directly relates to the principle of overload. SAID- specific adaptations to imposed demands. The SAID principle states that when the body is subjected to stresses and overloads of varying intensities, it will gradually adapt to over time to overcome whatever demands whatever demands are placed on it.
4. Consistency. The athlete must engage in a training and condition program on a consistent, regularly scheduled basis if it is to be effective.
5. Progression. Increase the intensity of the conditioning program gradually and within the individual athletes ability to adapt to increasing workloads.
6. Intensity. Stress the intensity of the work rather than the quantity. Coaches and athletic trainers too often confuse working hard with working for long periods of time. They make the mistake of prolonging the workout rather than increasing tempo or workload. The tired athlete is prone to injury.
7. Specificity. The program must be designed to address specific components of fitness relative to the sport in which the athlete is competing.
8. Individuality. The needs of individual athletes vary considerably. Adjust or alter training and conditioning programs accordingly to best accommodate the athlete.
9. Minimize stress. Expect that athletes will be close to their physiological limits as they can. Push the athletes as far as possible but consider other stressful aspects of their lives and allow time away from the conditioning demands of their sport.
10. Safety. Ensure a safe environment, proper techniques, and individual physiological limits.
The function of warm-up is to prepare the body physiologically for some upcoming physical work.
The purpose is to gradually stimulate the cardiorespiratory system to a moderate degree, thus producing an increased blood flow to working skeletal muscles and resulting in an increase in muscle temperature.
Moderate activity speeds up the metabolic processes that produce an increase in core body temperature. An increase in the temperature of skeletal muscle alters the mechanical properties of muscle. The elasticity of the muscle (the length to which the muscle can be stretched) is increased, whereas the viscosity (the rate at which the muscle can change shape) is decreased.
The warm-up should begin with 2 to 3 minutes of whole body activities to elevate the metabolic rate and raise core temperature. Once the athlete breaks into a light sweat, a period of sports specific stretching exercises should take place.
The warm-up should last for 10 to 15 minutes. The effects of stretching have been shown to last for about 6 minutes. Therefore, individuals are encouraged to remain loose.
The cooldown period enabled the body to return to a resting state. Such a period should last for about five to ten minutes. Proper cooldown decreases blood and muscle lactic acid levels more rapidly.
Flexibility is the ability to move a joint or series of joints smoothly and easily throughout the range of motion (ROM). Lack of flexibility can affect an individuals ability to move freely.
Factors that limit flexibility
Muscle and their tendons
RANGE OF MOTION
Active range of motion, also called dynamic flexibility, refers to the degree to which a joint can be moved by a muscle contraction, usually through the midrange of movement.
Passive range of motion, also called static flexibility, refers to the degree to which a joint may be passively moved to the endpoints in the range of motion. No muscle contraction is involved to move a joint through a passive range.
Ballistic stretching, which makes use of repetitive bouncing movements.
Static stretching, involves stretching a muscle to the point of discomfort and then holding it at the point.
Proprioceptive neuromuscular facilitation (PNF) uses alternating contraction and stretches
Agonist verse antagonist muscles
Agonist muscles, the muscle that contracts to produce a movement
Antagonist muscles, the muscle that is stretched in response to contraction of the agonist muscle.
Recommendations for holding a static stretch ranges from as short as 3 seconds to a long as sixty seconds. Recent studied found that 30 seconds may be an optimal time for holding a stretch. Static stretching should be repeated 3 to 4 times.
There are no significant findings in the effectiveness of ballistic and static stretching. Static stretching is general safer to perform.
All involve some combination of alternating contraction and relaxation of both the agonist and antagonist muscles. All three techniques use a ten-second-push phase followed by a ten-second relax phase.
Passive stretch antagonist (hamstring)
Contract antagonist (hamstring) and push against resistance (10 seconds)
Relax and contract agonist (quadriceps) (10 seconds)
Push-relax sequence is repeated at least 3 times
Contract-relax and hold-relax are variations of the slow-reversal-hold-relax technique
In the contract-relax method, the hamstrings are isotonically contracted so that leg actually moves toward the floor during the push phase.
The hold-relax method involves an isometric hamstring contraction against immovable resistance during the push phase.
NEUROPHYSIOLOGIC BASIS OF STRETCHING
All three stretching techniques are based on a neurophysiological phenomenon involving the stretch reflex. Every muscle in the body has mechanoreceptors that when stimulated inform the central nervous system of what is happening in the muscle. (muscle spindles, golgi tendon organs)
Both types of these receptors are sensitive to change in muscle length. The golgi tendon organs are also affected by changes in muscle tension.
When a muscle is stretched, the muscle spindles are stretched, sending sensory impulses to the spinal cord that informs the central nervous system that the muscle is being stretched. Impulses return to the muscle from the spinal cord, which causes the muscle to reflexively contract, thus resisting the stretch. If the stretch of the muscle continues for an extended period of time (at least 6 seconds), the golgi tendon organs respond (to the change in length and the increase in tension) by firing off sensory impulses of their own to the spinal cord. The impulses from the golgi tendon organs, unlike the signals from the muscle spindles, cause a reflex relaxation of the antagonist muscle. The reflex relaxation serves as a protective mechanism that will allow the muscle to stretch through relaxation before the extensibility limits are exceeded, causing damage to the muscle fibers.
Ballistic stretching is not continued long enough to allow the golgi tendon organs to have any relaxing effect. Impulses from the golgi tendon organs have the ability to override the impulses from the muscle spindles, allowing the muscle to reflexively relax after the initial reflex resistance to the change in length. Thus lengthening the muscle and allowing it to remain in a stretched position for an extended period of time is unlikely to produce any injury to the muscle.
The relaxation of the antagonist muscle during contractions is referred to as autogenic inhibition.
During the relaxing phase the antagonist is relaxed and passively stretched while maximal isotonic contraction of the agonist muscle pulls the extremity further into the agonist pattern. In any synergistic muscle group, a contraction of the agonist causes a reflex relaxation in the antagonist muscle, allowing it to stretch and protecting it from injury. This phenomenon is referred to as reciprocal inhibition.
Someone who is muscle-bound is not necessary limited in flexibility. Larger muscles may inhibit range of motion because of increased mass, but not because muscle itself is inflexible. Heavy weight training should be accompanied by a flexibility program.
Accurate joints range of motion can be measured by a goniometer.
THE IMPORTANCE OF MUSCULAR ENDURANCE
Muscular strength is the maximum force that can be applied by a muscle during a single contraction.
Muscular endurance is the ability to perform repetitive muscular contractions against some resistance.
Skeletal muscle contractions
Isometric contractions occur when the muscle contracts to increase tension, but there is no change in length of the muscle. Considerable force can be generated against resistance even no movement occurs. This is a static contraction.
In concentric contractions, the muscle shortens in length as a contraction is developed to overcome or move some resistance.
In eccentric contractions, the resistance is greater than the muscular force being produced and the muscle lengthens while continuing to contract. Concentric and eccentric contractions are both considered dynamic or isotonic.
There are three basic types of muscle fibers (metabolic rate, contractile capabilities)
Slow-twitch type I
Fast-twitch type IIa
Fast-twitch type IIb
Slow-twitch fibers are more resistant to fatigue than fast-twitch fibers; however, the time required to generate force is much greater in slow-twitch fibers. Because they are relative fatigue resistant, slow-twitch fibers are associated primarily with long-duration, aerobic-type activities.
Fast-twitch fibers (also referred to as type II fibers) are capable of producing quick, forceful contractions, but have a tendency to fatigue more rapidly than slow-twitch fibers. Fast-twitch fibers are useful in short-term, high-intensity activities, which mainly involve the anaerobic system. Fast-twitch fibers are capable of producing powerful contractions, whereas slow-twitch fibers produce a long-endurance type of force. There are two subdivisions of fast-twitch fibers. Although both types of fast-twitch fibers are capable of rapid contraction, type IIa fibers are moderately resistant to fatigue whereas type IIb fibers fatigue rapidly and are considered to be true fast-twitch fibers.
Factors that determine levels of muscular strength
Muscular strength is proportional to the cross-sectional diameter of the muscular fibers. The greater the cross-sectional diameter of the bigger a particular muscle, the stronger it is, and thus the more force it is capable of generating. The size of a muscle tends to increase in cross-sectional diameter with weight training. This increase in muscle is referred to as hypertrophy. Conversely, a decrease in the size of a muscle is referred to as atrophy.
Size of the muscle
Strength is a function of the number and diameter of muscle fibers composing a given muscle. The number of fibers is an inherited characteristic; thus an athlete with a large number of muscle fibers to begin with has the potential to hypertrophy to a much greater degree than does someone with relatively fewer fibers.
Strength is also directly related to the efficiency of the neuromuscular system and the function of the motor unit in producing muscular force. Initial increases in strength during a weight-training program can be attributed primarily to increased neuromuscular efficiency.
Strength in a given muscle is determined not only by the physical properties of the muscle itself, but also by biomechanical factors that dictate how much force can be generated through a system of levers to an external object. See figures 4-9, 4-10
Overtraining can result in psychological breakdown (staleness) or physiological breakdown, which may involve musculoskeletal injury, fatigue, or sickness. Engaging in proper and efficient resistance training, eating a proper diet, and getting appropriate rest can minimize the potential negative effects of overtraining.
If strength training is discontinued or interrupted, the muscle will atrophy, decreasing both the strength and mass. Adaptations in skeletal muscle that occur in response to resistance training may begin to reverse in as little as 48 hours.
Physiology of Strength Development
A number of theories have been proposed to explain why a muscle hypertrophies in response to strength training. Some evidence exists that the number of muscle fibers increase because fibers split in response to training. However, this research has been conducted in animals and should not be generalized to humans. It is generally accepted that the number of fibers is genetically determined and does not seem to increase with training.
Another hypothesis is that because the muscle is working harder in weight training, more blood is required to supply that muscle with oxygen and other nutrients. Thus the number of capillaries is increased. This hypothesis is only partially correct; few new capillaries are formed during strength training, but a number of dormant capillaries may become filled with blood to meet this increased demand for blood supply.
A third theory to explain this increase in muscle size seems the most credible. Muscle fibers are composed primarily of small protein filaments, called myofilaments, which are the contractile elements in muscle. These myofilaments increase in both size and number as a result of strength training, causing the individual muscle fibers themselves to increase in cross-sectional diameter. This increase is particularly true in men, although women also see some increase in muscle size. More research is needed to further clarify and determine the specific causes of muscle hypertrophy.
An isokinetic exercise involves a muscle contraction in which the length of the muscle is changing while the contraction is performed at a constant velocity. In theory, maximal resistance is provided throughout the range of motion by the machine.
Circuit training employs a series of exercise stations that consist of various combinations of weight training, flexibility, calisthenics, and brief aerobic exercises. A typical circuit would consist of eight to twelve stations, and the entire circuit would be repeated three times.
Calisthenics, or free exercises, is one of the more easily available means of developing strength. Isotonic movement exercises can be graded according to intensity by using gravity as an aid, by ruling gravity out, by moving against gravity, or by using the body part as a resistance against gravity. Most calisthenics require the athlete to support the body or move the total body against the force of gravity. Push-ups are a good example of a vigorous antigravity free exercise. To be considered maximally effective, the isotonic calisthenic exercise, as in all types of exercise, must be performed in an exacting manner and in full range of motion. In most cases, ten or more repetitions are performed for each exercises and are repeated in sets of two or three.
Plyometric exercise is a technique that includes specific exercises that encompass a rapid stretch of a muscle eccentrically, followed immediately by a rapid contraction of that muscle for the purpose of facilitating and developing a forceful explosive movement over a short period of time. The greater the stretch put on the muscle from its resting length immediately before the concentric contraction, the greater resistance the muscle can overcome. Plyometric exercises emphasize the speed of the eccentric phase.
STRENGTH TRAINING FOR THE FEMALE ATHLETE
Is dependent on the presence of testosterone. Testosterone is considered a male hormone. Women with higher testosterone levels tend to have more masculine characteristics. Perhaps to most critical difference between males and females regarding physical performance is the ratio of strength to body weight. The reduced strength-to-body weight ratio in women is the result of their higher percentage of body fat. This ratio is reduced by strength training.
Cardiorespiratory endurance is the ability to perform whole-body muscle activities for extended periods of time.
The greatest rate at which oxygen can be taken in and used during exercise is referred to as VO2 max. Its a coordinated effort between the heart, lungs, blood vessels, and blood.
Interval training is alternating periods of work with periods of active recovery.