What is high intensity resistance training?

High-Intensity Resistance Training: Definition and Parameters

High-intensity resistance training is defined as exercise performed at ≥60-80% of one-repetition maximum (1-RM), typically involving 8-12 repetitions for healthy adults under 60 years, or loads ≥80% of 1-RM with fewer repetitions (≤7 reps) for maximal strength development. 1, 2

Core Training Parameters

High-intensity resistance training is characterized by specific load thresholds that distinguish it from moderate or low-intensity approaches:

• Load intensity: 60-80% of 1-RM for general strength and hypertrophy, or ≥80% of 1-RM for maximal strength development 1, 2
• Repetition ranges: 8-12 repetitions at 60-80% 1-RM for balanced strength and endurance gains in adults under 50-60 years 1
• Frequency: 2-3 days per week with adequate recovery between sessions 1
• Volume: 1-3 sets of 8-10 different exercises targeting major muscle groups 1
• Duration: Training sessions typically last 30-45 minutes 1

Physiological Mechanisms

High-intensity resistance training recruits more high-threshold motor units and optimizes neural adaptations essential for maximal strength, which distinguishes it from lower-intensity approaches. 2

The intensity threshold matters because:

• Loads ≥60% of 1-RM are necessary to activate the complete spectrum of fiber types, particularly those associated with the largest motor units 3
• Training at ≥80% of 1-RM produces superior improvements in maximal strength compared to moderate or lower load training 2
• High-intensity protocols (85% 1-RM) have demonstrated significant reductions in total cholesterol and LDL cholesterol in research studies 1

Practical Application Guidelines

For maximal strength development, use 3-5 repetitions with heavier weights (≥80% of 1-RM) and allow for adequate rest between sets (2-3 minutes). 2

The American Heart Association provides specific exercise selection recommendations:

• Lower extremity exercises: leg extensions, leg curls, leg press 1
• Upper extremity exercises: bench press, lateral pulldowns, biceps curl, triceps extension 1
• Core exercises: lower back extension, abdominal crunch/curl-up 1

Progressive Overload Strategy

The relative load should be increased when the individual can comfortably exceed the repetition range for two consecutive sessions. 1

Progressive overload is achieved through:

• Increasing resistance/weight when current workload can be performed for 1-2 repetitions over target range 1, 4
• Systematically advancing training intensity as fitness level improves 1
• Implementing daily undulating periodized resistance training (alterations in volume and intensity on a daily basis) may be advantageous, though data are limited 1

Special Population Modifications

For cardiac patients and healthy older adults (≥50-60 years), a modified approach using 10-15 repetitions at lower relative resistance (40-60% of 1-RM) is recommended for injury prevention. 1, 2

The rationale for this modification:

• Higher intensity efforts with fewer repetitions can have adverse effects on the knee (leg extension) and shoulder (rotator cuff) areas in older populations 1
• The single greatest cause of musculoskeletal injury with resistance training is a previous injury 1
• Lower intensity with higher repetitions still provides meaningful strength gains while reducing injury risk 1

Clinical Benefits Beyond Strength

High-intensity resistance training confers multiple health benefits:

• Muscle mass and strength: Greater potential to improve muscle mass and strength than endurance training alone 1
• Functional capacity: Improves ability to perform activities of daily living and decreases fall risk in older adults 1
• Metabolic effects: Increases basal metabolic rate and improves insulin sensitivity 5
• Cardiovascular benefits: Reduces blood pressure and improves blood lipid profiles 5
• Symptom tolerance: Results in less dyspnea during exercise compared to endurance training, making it more tolerable for individuals with respiratory disease 1

Common Pitfalls to Avoid

Using exclusively one repetition range limits overall development—combining different loading schemes may provide optimal results. 2

Critical safety considerations:

• Proper screening: Individuals must be carefully screened for cardiovascular limitations and preexisting orthopedic/musculoskeletal problems before initiating high-intensity resistance training 1
• Technique priority: Improper technique at heavy loads increases injury risk—prioritize form over weight 2
• Breathing pattern: Avoid breath-holding and straining (Valsalva maneuver) by exhaling during contraction and inhaling during relaxation 2
• Progressive approach: For beginners, focus on proper technique with moderate loads (8-12 repetitions) before progressing to more specialized high-intensity protocols 2

Comparison with Lower Intensity Approaches

Research indicates that low- to moderate-intensity resistance training (50-75% 1-RM) results in greater benefit to the lipid profile than very high-intensity resistance training (90-110% 1-RM), though the mechanisms underlying this difference remain unclear. 1

This creates a nuanced picture:

• For lipid profile improvements, moderate intensity (50-75% 1-RM) may be superior to very high intensity (≥90% 1-RM) 1
• For maximal strength and power development, high intensity (≥80% 1-RM) remains the gold standard 2, 4
• Training loads between 50-80% of 1-RM can improve endurance exercise capacity in some populations 1