Take a deep dive into what mechanical stress is, & why it is important in the resistance training world. 

When it comes to resistance training & weightlifting, mechanical stress (& tension) is a critical concept to understand. Mechanical stress will influence technique/form, performance, and risk of injury. 

Mechanical tension is one of the primary drivers for hypertrophy & strength development. Why does mechanical tension matter so much?

• Muscle fiber recruitment
• Strength development 
• Stimulation of muscle protein synthesis
• Progressive overload
• Hypertrophy & the role of Time under tension 
• Muscle loss prevention

Things to focus on when maximizing mechanical tension:

1. Heavy lifting, but emphasizing good mechanics/form.
2. Utilizing full ranges of motion 
3. Control your eccentrics. Slow your movement down. 
4. Progressive overload or increase overload variables! 
5. Near failure & complete failure training

Studies supporting mechanical tension:

The study emphasizes that mechanical tension, achieved through resistance training, is essential for maximizing hypertrophic responses. journals.lww.com

The findings in this study suggest that mechanical tension, induced by appropriate training loads and techniques, is a significant contributor to muscle mass and strength development. frontiersin.org

The review discusses how mechanical tension, particularly when muscles are stretched under load, plays a vital role in muscle growth and strength adaptations. link.springer.com

The study found that training closer to failure can enhance muscle growth, likely due to increased mechanical tension from higher motor unit recruitment. link.springer.com

This website shows that architectural changes contribute to greater mechanical tension during contractions. Not a peer review article! https://en.m.wikipedia.org/wiki/Architectural_gear_ratio?utm_

What is the relationship between time under tension & mechanical tension?

Time under tension & mechanical tension do not always correlate, & here is why:

• Mechanical tension is primarily driven by force production or the amount of force a muscle can generate in response to resistance. 
• More time under tension doesn’t always mean more mechanical tension.
• Heavier loads will typically generate higher rates of mechanical tension. 
• Higher tension rates means higher fiber activation rates.
• Muscles under high stretch during the resistance of force will experience high mechanical tension. 

When does more time under tension mean more mechanical tension?

• Heavy enough loads, as well as controlling the movement. This increases mechanical tension by keeping muscles under strain longer.
• Too light of load makes this inefficient. Can just increase metabolic stress instead. 
• Too slow!!! TUT can reduce force production if reps are excessively long. Mechanical tension can reduce. 
• To maximize mechanical tension, you want a balance of heavy loads & sufficient TUT—typically by controlling eccentrics, lifting explosively during concentrics, & training close to failure.

Studies that support the correlation between TuT & mechanical tension:

This study shows high mechanical tension is achieved by lifting heavy loads, which leads to greater muscle fiber recruitment and stimulates anabolic signaling pathways essential for muscle growth.pubmed.ncbi.nlm.nih.gov

This study shows longer TUT can enhance metabolic stress and muscle damage, both of which are associated with hypertrophy. However, the relationship between TUT and hypertrophy is complex. pmc.ncbi.nlm.nih.gov

This study shows mechanical tension primarily stimulates muscle growth through high-force contractions, whereas TUT influences growth by increasing metabolic stress and muscle fatigue.pubmed.ncbi.nlm.nih.gov

This study shows that lifting heavy weights (to increase mechanical tension) and controlling the tempo of exercises ensures muscles remain under tension for an optimal duration. muscleandmotion.com

The researchers found that longer TUT, achieved by slowing down repetitions, led to a more sustained increase in muscle protein synthesis post-exercise, suggesting a potential benefit for muscle growth.ncbi.nlm.nih.gov

The study highlighted that mechanical tension stimulates anabolic pathways within muscle cells, leading to protein synthesis and muscle growth. frontiersin.org

The article suggests that maintaining muscle tension for a certain period during resistance training is beneficial for muscle growth. livescience.com

Let’s break down what the 2 different types of mechanical stress are!

Compressive stress: Compressive stress is simply stress that bones & joints experience as they bear external load/weight during resistance training. For example, the experience your spine undergoes when barbell squatting. Due to the stress of the external load & natural force compressing the spine.  

Tensile Stress: This form of mechanical stress occurs in muscle & tendons when resistance training.  Contracting/pulling against each other. For example, the biceps brachii & long head bicep tendon experience tensile stress through all phases of the movement. 

Why is it important to understand mechanical stress?

1. Proper biomechanics: Posture, kinetic chain, alignment, form, and proper technique is important to ensure that mechanical stress is distributed evenly. If form is neglected, uneven stress can be experience on the joints & muscles. This will increase the risk of tears and strains. 
2. Progressive overload: This method of gradual increases in weight will help musculature and surrounding tissue adapt to higher amounts of mechanical tension. This will promote strength and hypertrophy, while minimizing the risk of injury (if integrated properly). I do not recommend too high of overload jumps. Stick within 2.5-10LBs. each set (dependent on the exercise).
3. Keep in mind —>Recovery: adequate recovery is essential! Muscle & connective tissues now have time to repair from the mechanical stresses they experience. Essential for long term injury prevention.

How may knowledge of this concept affect your training?

1. Injury prevention: Knowledge of mechanical stress will lead to improved & better developed warm-up routines. Along with improved recovery strategies & lifting techniques. Do not neglect better ways of training!
2. Performance: Understand stress & tension & its effects on the body will help with development in training & exercise programs. It sure plays a big role when I develop custom programs.
3. Program design: Allows me to tailor programs & ensure clients experience the right amount of mechanical tension in correlation to their goals. Whether it is fat loss, endurance, hypertrophy, strength, etc, this is highly important. 

Improve strength & hypertrophy, optimize performance, prevent injury & enhance recovery, & all around allow your body to experience better adaptation!