The effects of strength training on the human body and physiology

Strength training is an essential component of fitness; it goes beyond building muscle and strength to have profound effects on human physiology, including muscle growth, fat metabolism, movement efficiency, and even mental health. This article provides a comprehensive overview of physiological responses and best practices in strength training and is a step-by-step guide for both fitness enthusiasts and beginners.

1. The science behind muscle hypertrophy and anatomy

Muscle hypertrophy, or the growth of muscle cells, occurs through complex biological responses as a result of resistance training. Skeletal muscle is made up of two basic types of muscle fibers: Type I (slow-twitch) and Type II (fast-twitch). Type I fibers are used in activities that require endurance, while type II fibers, especially type IIb, generate more force and are mainly used in high-intensity movements.

Strength training stimulates muscle hypertrophy via two main pathways:

• Mechanical tension: When muscles lift heavy loads, the tension on muscle fibers triggers biochemical signals that promote muscle protein synthesis.
• Metabolic stress: The accumulation of metabolites (such as lactate) from training at high repetitions can also stimulate muscle growth by increasing the production of anabolic hormones.

During resistance training, muscle fibers undergo micro-tears. The body repairs these tears by activating satellite cells, producing thicker and stronger fibers. Progressive loading, or gradually increasing resistance, is key to consistently stimulating these fibers, as muscles quickly adapt to resistance over time.

2. The metabolic effects of strength training on fat loss

The benefits of metabolic strength training extend beyond burning calories during exercise. While aerobic exercise is effective at burning immediate calories, strength training contributes to an increased resting metabolic rate, which helps you lose fat even at rest. Research shows that each pound of muscle can burn about 6-10 extra calories per day.

• Acute effects: During a strength training session, the body enters a state of oxygen debt known as excess post-exercise oxygen consumption (EPOC), which keeps the metabolism elevated for hours after exercise.
• Long-term benefits: Over time, strength training increases muscle mass, which increases your resting metabolic rate. Increased muscle mass also improves the body's sensitivity to insulin, helping to regulate blood sugar and reduce fat accumulation.

Incorporating strength training regularly has a lasting effect on fat metabolism, making it beneficial for long-term weight management and overall metabolic health.

3. Optimal recommendations for training repetition: Based on research

Optimal recommendations for the frequency of strength training vary based on factors such as experience level, age, and the individual's ability to recover. Research generally recommends the following:

• Beginners: Two to three full-body exercise sessions per week, focusing on basic movements, allowing ample time for recovery.
• Intermediate trainees: Three to four sessions per week with a split routine (e.g. upper/lower body) helps to focus on specific muscle groups while maintaining a balanced recovery.
• Advanced athletes: Four to six sessions per week, often with a customized split (e.g. push/pull/legs), which increases muscle hypertrophy and endurance, especially when progression is used.

Older adults and individuals with lower recovery capacity may benefit from lower training frequencies, ensuring adequate rest to minimize the risk of injury.

4. Basic strength exercises by movement patterns

Understanding basic movement patterns is essential in building effective training programs. Each movement pattern can be linked to exercises that target multiple muscle groups, contributing to functional strength.

• Push-ups (e.g., chest exercise, shoulder exercise): Targets the chest, shoulders, and triceps. Emphasize pulling the shoulder blades to protect the joints.
• Pull-ups (e.g., rowing, calves): Strengthens the back and biceps. Keep the spine in a neutral position and focus on activating the back muscles.
• Squats (such as back and front squats): Targets the muscles of the thighs and buttocks. The chest should be lifted and avoid excessive leaning forward to maintain proper form.
• Hinge (like the deadlift): Works the posterior chain, including the hamstrings, glutes, and lower back. It is important to learn proper hinge mechanics to avoid lower back strain.
• Pregnancy (e.g., weight lifting): Strengthens core muscles, promotes balance, and helps with grip strength and overall stability.

Each movement pattern has many variations, such as a chest exercise in a push-up, or a Romanian pull-up in a hinge. Using variations can reduce boredom and stimulate the muscles in different ways, preventing stopping progress.

5. Typical weekly training programs for different levels

A program for beginners (2-3 days per week):

• Day 1: Full Body (squats, push-ups, rowing)
• Day 2: Rest or light cardio
• Day 3: Full Body (deadlift, shoulder press, weighted deadlift)
• Concentration: Light to medium weights, focus on form and movement control.

Intermediate level program (3-4 days per week):

• Day 1: Upper (chest, rowing, biceps curls)
• Day 2: Bottom (squats, lunges, leg curls)
• Day 3: Rest or flexibility exercises
• Day 4: Full-body workouts (push-ups, deadlifts, planks)
• Concentration: Medium weights with gradual progression, introducing compound exercises and flexibility.

Advanced level program (5-6 days per week):

• Day 1: Push-ups (chest workout, shoulder workout, triceps workout)
• Day 2: Pull-ups (calisthenics, rowing, back workout)
• Day 3: Legs (back squats, lunges, leg exercises)
• Day 4: Basic exercises and fitness
• Day 5: Push or Pull (focus on variations)
• Day 6: Active recovery or flexibility exercises
• Concentration: Higher intensity with planning in the progression, introducing additional exercises to address muscle imbalances.

6. The role of progressive loading and cyclical planning

To achieve continuous progress, it is necessary to apply the principles of progressive loading and periodic planning:

• Gradual loading: Gradually increasing weight, repetitions or volume in exercises. Without this progression, the muscles adapt to the current loads, which stops growth.
• Cyclical planning: Organizing training into cycles (short, medium, long) helps manage intensity and volume over time. For example, one cycle could focus on hypertrophy (6-12 repetitions) for several weeks, followed by a strength cycle (1-5 repetitions). Cyclic planning minimizes the risk of overtraining by providing periods of lower intensity.

These strategies allow for sustainable adaptations by challenging the muscles in a variety of ways, supporting recovery and optimizing performance.