Practical Guide to Hip and Knee Strengthening

Original Editor - Wanda van Niekerk based on the course by Lee Herrington

Top Contributors - Wanda van Niekerk and Jess Bell  

Progressive Overload for Strength Development

The following points highlight general principles that should be considered with progressive overload.

• Please remember the following TWO points when working with a patient who requires a strengthening programme:
  • establish the level of load they can currently cope with
  • keep reassessing the situation as the patient progresses
• Progressively expose an individual to load at a tissue and system level
• Allow sufficient recovery time to enable adaptation
• Application of the appropriate load is needed to drive the required adaptation
• Specific Adaptation to Imposed Demand (SAID) principle
  • adaptations produced by training are highly specific to the nature of the stimulus or overload applied
  • adaptations are specific to strength, power, endurance, functional activity, joint angle, sequence of muscle activations, energy systems and virtually all other variables present
  • the SAID principle is impacted by:
    • position or length of the muscle (length-tension relationship)
    • speed of contraction (force-velocity relationship)
    • muscle contraction type (isometric, concentric, eccentric)
    • repetition maximums
      • the repetition continuum or strength-endurance continuum is usually used to give specific loading recommendations
        • for muscle strength, use low repetitions with heavy loads: 1-5 repetitions per set with 80-100% of 1-repetition max (1RM)
        • for muscle hypertrophy, use moderate repetitions with moderate loads: 8-12 repetitions per set with 60-80% of 1RM
        • for muscle endurance, use high repetitions with light loads: 15+ repetitions per set with loads below 60% of 1RM
      • if you would like to read more, please see: Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum
    • percentage (%) repetition maximum
      • training as a percentage of repetition maximum (RM)
        • e.g. 80% of 1 RM
          • the 1 RM strength test assesses the maximal strength of the muscle groups engaged during a single specified movement. Read more about 1 RM here.
      • repetitions to failure
        • maximum number of repetitions a person can lift to failure
          • e.g. 80% of 1 RM = 7-10 repetitions to failure
• If you'd like, you can read more about:
  • Neuromuscular adaptations to exercise
  • Principles of exercise physiology and adaptation
  • Chronic musculoskeletal adaptations to exercise
• Please read this article if you would like to learn more about the DAPRE system: The Daily Adjustable Progressive Resistance Exercise System: Getting Reacquainted With an Old Friend
• Optionally, you can also read more about the principles of rehabilitation here. This article covers where to start, underpinning theories, key issues when reloading injured tissues, monitoring the impact of load and progressing load.

Isolated Muscle Work Around the Muscles of the Hip and Knee

Isolated muscle work is often presented as the amount of electromyographic (EMG) activity. It is important to know that for strengthening purposes, the level of EMG activity needs to be greater than 70-80% of an individual's maximum isometric voluntary contraction (MIVC). Repetition to failure of a selected exercise must be between 8-10 repetitions for strength training.

Gluteus Maximus

Table 2 shows examples of exercises for gluteus maximus recruitment. The percentage maximum isometric voluntary contraction (MIVC) is shown to indicate the rank order for these exercises. The addition of bands to weight-bearing activity will significantly increase gluteus maximus activity.

Table 2. Rank order of exercises for recruitment of gluteus maximus based on EMG (adapted from Boren et al.)

Exercise	% MIVC
Front plank with hip extended	100
Single leg squat	72
Side plank	71
Lateral step up	64
Single leg deadlift	59
Forward step-up	55
Single leg bridge	54
Hip clam	53

Below are some examples of exercises targeting gluteus maximus.

Progression of bridging exercise

The four videos below provide an example of progressing the bridge exercise. Performing a unilateral bridge with the other leg straight (lengthened lever arm) produces significantly greater EMG activity than a unilateral bridge with the other leg in 90 degrees hip flexion and 90 degrees knee flexion (shortened lever arm) in the gluteus maximus and gluteus medius muscles. The addition of a band to the exercise further increases gluteal activity.

Barbell hip thrust versus squat or split squat

For patients who cannot tolerate a high load very well (e.g. a patient with spinal problems), consider a hip thrust type of exercise with a weight across the pelvis instead of a squat or split squat exercise. The barbell hip thrust exercise produces greater gluteus maximus activity than the back squat and split squat. Two examples of a hip thrust exercise are shown in the videos below.

Gluteus medius

Table 3 shows the rank order of exercises for recruitment of gluteus medius based on EMG activity. The addition of bands has also been shown to increase gluteus medius activity significantly.

Table 3. Rank order of exercises for gluteus medius recruitment based on EMG activity (adapted from Boren et al.)

Exercise	%MIVC
Side plank	100
Single leg squat	82
Front plank hip extended	75
Hip abduction in sidelying	63
Lateral step up	60
Single leg deadlift	56
Forward step-up	55
Single leg bridge	55
Hip Clam	47

Below are some examples of exercises targeting gluteus medius.

Summaries of articles focusing on hip rehabilitation exercises

• Electromyographic analysis of gluteus medius and gluteus maximus during rehabilitation exercises: This article provides a list of exercises and the percentage MIVC of the gluteal muscles that occurs during these exercises. Images and instructions for all exercises are also provided.
• Gluteal muscle forces during hip-focused injury prevention and rehabilitation exercises: This article compares and ranks muscle forces in eight hip-focused exercises. The exercises were performed with and without external resistance. Underlying fibre lengths, velocities and muscle activations were described by inputting data from motion capture, ground reaction forces and EMG into an EMG-informed neuromusculoskeletal model. Gluteus maximus, medius and minimus muscle forces were estimated in this model.
  • Tier 1 exercises for Gluteus maximus were:
    • loaded split squat, loaded single leg Romanian deadlift, loaded single-leg hip thrust
  • Tier 1 exercises for Gluteus medius were:
    • body weight side plank, loaded single leg squat, loaded single leg Romanian deadlift
  • Tier 1 exercises for Gluteus minimus were:
    • loaded single leg Romanian deadlift, body weight side plank
  • Useful blog post to read: Hip-focused injury prevention and rehabilitation exercises: How to choose which one?
  • Useful infographic: Gluteal muscle forces during hip-focused injury prevention and rehabilitation exercises

Hip Adductors

The rank order of exercises for the recruitment of adductor longus based on EMG is shown in Table 4.

Table 4. Rank order of exercises for adductor longus recruitment based on EMG activity (adapted from Serner et al.)

Exercise	Mean peak normalised EMG (nEMG)% of MVC (adapted from Serner et al.)
Copenhagen adduction	110%
Isometric adduction with a ball between ankles	100%
Isometric adduction with ball between knees	86 %
Hip adduction sidelying	64 %

Below are examples of some of the adductor exercises.

Hamstrings

"Hamstrings are activated differently during hip-based and knee-based tasks." Hip extension exercises, such as straight leg raise bridge or a unilateral stiff-leg deadlift (or Arabesque or single-leg Romanian variation in a Romanian deadlift), load the biceps femoris more, while the Nordic hamstring exercise recruits semitendinosus more.

Quadriceps

The basic open chain knee extension exercise is a useful exercise for developing quadriceps strength. In patients with weakness in the shortened position of the quadriceps, it may be useful to add the isolated band pullback exercise to isolate the inner range position and develop strength in this range.

Adapting Closed Chain Exercises for Either Knee or Hip Bias

The relative contribution of the knee or hip to a squatting task is influenced by:

• the amount of load during a deadlift and lunge
• the trunk position
• the limb position