Flexibility and Strength Training: Impact and Methods

Posted on Dec 18, 2024 in Physical Education

Flexibility: A Key Component of Physical Fitness

Flexibility is a fundamental physical quality that is essential for any fitness plan. It is the ability to perform movements with maximum amplitude, involving either a specific body part or the entire body. The degree of flexibility a person possesses depends on:

• Muscle elasticity: The ability of the muscle to lengthen and shorten without deformation, returning to its original form.
• Joint mobility: The degree of movement each joint allows, which varies from person to person.

Insufficient flexibility can result in:

• Deformations caused by the adoption of certain positions.
• Increased risk of muscle injuries.
• Incorrect technique in sports movements due to a lack of range.

Factors Influencing Flexibility

• Inheritance: Genetic characteristics are the primary conditioning factor. Some individuals are naturally more flexible than others from birth.
• Sex: Physiological differences between sexes mean that women are generally more flexible.
• Age: Flexibility is highest in the early years of life and tends to decrease with age.
• Usual type of work: Postures and movements performed regularly in daily activities can increase or decrease flexibility.
• Time of day: Flexibility is minimal upon waking, increases throughout the day, and decreases again towards the end.
• Temperature: Muscle temperature, the degree of muscle fatigue, and training also influence flexibility.

Methods of Flexibility Training

Basic methods for developing flexibility include active, kinetic, passive, and contraction-stretching methods. Limited mobility can cause impaired coordination, increased risk of musculoskeletal injuries, impaired quality of movement, difficulty refining sports techniques, and postural defects.

The primary goal of flexibility training is to maintain flexibility levels, preventing the decrease that can be caused by a lack of adequate exercise, age-related changes, or the exclusive practice of a particular sport.

Strength: A Fundamental Physical Quality

Strength is considered by some authors to be the most important physical quality from a sports performance standpoint. Any movement requires the application of force. One of the best definitions of force is:

Force is the tension that a muscle can develop against resistance.

• Static force: Tension against resistance without displacement.
• Dynamic force: Tension that displaces or overcomes resistance. This force can be further classified as:
  • Maximum power: The ability to mobilize a maximum load, regardless of time (e.g., weightlifting).
  • Strength-resistance: The ability to apply a non-maximal force over a prolonged period (e.g., rowing).
  • Explosive force (power): The ability to mobilize a non-maximal load in the shortest possible time (e.g., throwing, jumping, sprinting).

The coordinated action of all joints and muscles involved in the execution of a movement is called the kinetic chain. The kinetic chain always starts from the point of support and extends to the last segment involved in the movement. A clear example is the medicine ball throw.

Factors Determining Strength

• Physiological and anatomical factors:
  • Transverse section of muscle: A thicker muscle is stronger.
  • Predominant fiber type: A higher percentage of white fibers results in greater strength.
  • Muscle length: Longer muscle fibers allow for greater contraction and, therefore, more force.
  • Muscle innervation: More innervated muscle fibers lead to a greater capacity for contraction.
• Physical-mechanical factors:
  • Joint angulation: 100% strength is reached at around 90 degrees; at 180 degrees, about 40% of maximum strength is lost.
  • Pre-stretching of muscle: If not excessive, it favors greater contraction and more effective force.
• Psychological factors: Motivation, attention, concentration, willpower, and spirit of sacrifice significantly influence strength. Emotional states also modify muscle force through nervous discharges.
• Other factors:
  • Sex: Men generally have greater strength than women due to higher concentrations of muscle-mass-increasing hormones.
  • Age: Strength is similar in boys and girls until around 12. In boys, it increases significantly from 14 to 17, peaking around 30. In girls, the increase is less noticeable, peaking around 20-25. Strength begins to decrease after these ages.
  • Food: A balanced intake of proteins, carbohydrates, fats, minerals, and vitamins is crucial for muscle strength.
  • Muscle temperature: A good warm-up increases effective force by improving blood flow and oxygen delivery to muscles.
  • Room temperature: Moderate temperatures enhance contraction ability, while excessively low or high temperatures reduce it.
  • Fatigue: Fatigue diminishes the intensity and extent of muscle contraction and can cause injuries.
  • Degree of training: Training increases muscle contraction capacity, while excessive rest decreases it.

Positive Effects of Strength Training

• Increased muscle fiber thickness (hypertrophy), leading to increased strength.
• Increased number of blood capillaries in the muscle.
• Increased muscle myoglobin, facilitating oxygen transport and improving capacity and duration.
• Increased energy stores in the muscle (glycogen, ATP, CP).
• Improved intramuscular coordination.
• Increased muscle tone, aiding in maintaining correct posture.
• Fat and water loss.

Risks of Strength Training

Strength training can lead to damage if not done correctly. Some negative impacts include:

• Joint injuries.
• Negative impact on bone growth if excessive loads are applied during growth ages.
• Spinal cord deformations if exercises are performed with poor posture or excessive weight.
• Tendon and muscle injuries when performing exercises abruptly or under unfavorable conditions.
• Excessive weight gain, which can be detrimental to some athletes.
• Impaired speed, coordination, and endurance if exercises are performed slowly with excessively heavy loads and few repetitions.
• Impaired flexibility if contractions are performed incompletely without using the maximum range.

Considerations for Strength Training

To maximize benefits and avoid risks:

• Avoid exercises with a bent back.
• When lifting weights, keep them close to the body’s center of gravity.
• Bend the knees when lifting weights from the floor.
• Strengthen thoracic and abdominal muscles before progressive strength training.
• Increase loads gradually.
• Work on strengthening both sides of the body equally.

Strength Training Methods

An initial check should be performed to assess the athlete’s level. It is recommended to:

• Select exercises to quickly produce the desired goal, initially aiming for multilateral development of all muscle groups, then focusing on those most necessary for the athlete’s sport.
• Training at the beginning depends mainly on the results obtained from testing each exercise. Loads should not exceed 20-40% of the maximum obtained in previous tests.
• Vary training loads to avoid monotony and stagnation.
• Vary training systems for continuous improvement.
• Ensure training continuity, as strength is lost if muscles are not exercised.
• Allow for adequate recovery after exertion, but do not let the muscle cool down completely. Gentle exercises, especially those promoting elasticity and muscle relaxation, can be inserted during breaks.
• Clearly define objectives and the type of force to be developed.
• For maximum strength, work with large loads and low repetitions.
• For power, use medium loads with fast execution and a moderate number of repetitions.
• For strength-resistance, use small loads and a high number of repetitions.

Training Systems for Strength Development

• Circuit training: Simple exercises using body weight, with or without materials to increase effort. Suitable for beginners and can be used in schools until 14-16 years old. Used to improve basic strength and strength-resistance.
• Overload systems: Use external loads, including light materials, partner’s weight, or heavy weights (weightlifting, bodybuilding).
• Training with a partner: Includes pushing, dragging, traction, transport, and control exercises.
• Weightlifting: Uses submaximal loads between 80-100% of the individual’s potential. Few exercises per session (5-8) and few repetitions (1-3 for maximum load, 5-8 for submaximal). Complete recovery is essential.
• Plyometrics (multihop): Repetitive jumps in various ways (height, length, different supports, obstacles, starting/arrival positions, uphill/downhill, stairs).
• Multithrows: Repetition of throws to improve upper body and trunk strength, also applicable to lower limbs. Uses lighter items like medicine balls.
• Isometrics: Based on isometric contractions (no joint movement). Short-duration contractions (4-6 seconds) with maximum effort against resistance. Applied at different angles (45, 90, 135 degrees). Hard, boring, and should not be the sole training system.

Advantages of Isometrics

• Useful in injury recovery.
• Easy to apply without equipment.
• Effective for rapid strength gains.
• Allows for isolated muscle training.

Disadvantages of Isometrics

• Monotonous.
• Negatively impacts flexibility.
• Does not improve coordination.
• May not improve muscle vascularization.