Grip strength and wrist mobility
Grip strength and wrist mobility in a weightlifter… and in you
A weightlifter presents with grip weakness and poor wrist mobility. We explore how these two factors relate biomechanically
I recently saw a man in his mid forties, a weightlifter. Let’s call him Sam. Sam came to me complaining of a variety of mild pains related to his sport: lower back, neck, shoulder. Overall quite a stiff guy, but strong. What was most interesting, and what this post is about, was his reported sense of deteriorating grip strength.
He had lifted heavy weights for about 20 years, but had noticed gradually over the last four or five that his grip seemed to keep failing him quicker. He noticed this particularly when dead-lifting, and with rowing movements. He said that he was always fine on his warm up sets, but as soon as he started to put any meaningful weight on the bar his grip fatigued well before the rest of his body had had a chance to do enough work. He had added in the usual wrist curls as an attempt to strengthen up, but felt that he had made no progress.
Anybody complaining of neck pain and upper extremity weakness as Sam was, warrants a neurological examination to check the health of the nerves of the brachial plexus. Motor symptoms in the upper extremity without numbness is rare, and is usually proceeded by some radicular pain. Sam denied any altered sensation in the hands, his: reflexes, sensory testing, and myotomes were all normal, and provocative test of the neck didn’t lead to any extremity symptoms.
As noted, Sam was generally quite stiff - his hips did not allow sufficient flexion and external rotation to maintain a neutral lumbar spine in a thigh-parallel squat, and he struggled to hold his arms overhead especially while moving the back - points to be addressed regarding his lower back, neck and shoulder complaints. As you can probably predict, we also found that wrists to have poor range of motion - a key, but perhaps not obviously relevant finding for grip strength.
Time for some anatomy
TL;DR Both the extensors of the wrist, and the flexors of the fingers span multiple joint - are ‘multi-joint’ muscles. Multi-joint muscle actions can be modified by their relationship between other joints and muscles. Wrist extension improves the action of the finger flexors.
The two principle flexors of the fingers: the flexor digitalis superficialis, and the flexor digitalis profundus both act together to curl all the fingers into a fist - or to wrap the fingers around an object - such at a bar. Both these muscles have their origin, along with the flexors of the wrist, at the medial epicondyle of the humerus (the pointy bit of bone just inside your elbow). This makes these muscles very much multi-joint muscles (crossing the finger joints, the wrist joints, and to an extent the elbow joint). Another important multi-joint group of muscles are the wrist extensors (extensor carpi ulnaris, extensor carpi radialis: longus and brevis) spanning from the lateral epicondyle of the humerus to the back of the wrist.
Multi joint muscles can perform complex, perhaps paradoxical actions. Just as the hamstrings can extend the knee, the wrist extensors can in fact flexor the fingers.
Fully relax the wrist into flexion. Keep the fingers relaxed and slowly extend the wrist. Feel the fingers naturally close, as if gripping a bar?
Next, make a tight fist with the wrist in neutral, and then gripping the tightness in the fingers, extend the wrist. Feel a further tensioning through the palm and the fingers?
These two examples should help to demonstrate demonstrate why wrist extension is important for grip strength in that active wrist extension helps to create increased relative flexion of the fingers. The origin of the finger flexors at the elbow, and their attachment on the phalanges, are taken further apart when the wrist is extended.
The two relevant variables when thinking about the role of wrist extension in grip strength are: extension range of motion in the wrist, and the ability of the extensors of the wrist to actively perform this movement, concentrically, or isometrically.
What’s the evidence?
TL;DR Experimental evidence shows that although different individuals opt for varying degrees of wrist flexion/extension for power grip, most individuals get maximum grip strength between 30 and 45 degree of wrist extension, and rely upon their wrist extensor muscle group for generating torque.
Suzuki (2012) experimentally paralyzed the wrist extensors via a radial nerve block and found an average decrease in peak grip strength of 34%. In fact the role of active wrist extension has been theorised to increase in importance with sustained contraction, as a anti-fatigue mechanism (Johnston, Bobich, Santello, 2010).
Although every body varies slightly, and will perform certain tasks - like power gripping - most efficiently with variable joint angles, numerous studies suggest that, on average, grip strength is enhanced with wrist extension. Shimose, Matsunaga, and Muro (2011) found that when asked to perform a peak grip task a mean 30 degree wrist extension angle was used - but with a range between 70 extension and 10 flexion. Bhardwaj. et al (2011) then found that when people's wrists were splinted at: 45, 30 and 15 degree of extension, neutral, and 30 flexion, 45 extension was found to produce the greatest peak torque in grip strength testing.
So this all shows that, experimentally, individuals on average have greater grip strength with ranges of wrist extension greater than Sam is able to achieve. We also know from research that Sam lacks the ranges of motion deemed necessary to perform a range of normal daily activities (Ryu, et al 1991) another reason to summise that something is sub-optimal here.
I don’t believe in labelling any and all morphological variation as a pathological, and embrace the multitudes and possible motors strategies the human body can manifest - I believe that what we find in Sam us worthy of some attention, and is highly likely to be related to his complaint.
I will explore how we approached improving this range of motion, and the principles involves in a following blog post.
Ryu. JY, Cooney. WP, Askew. LJ, An. KN, Chao. EY. (1991). Functional Ranges of Motion of the Wrist and Joint. Journal of Hand Surgery American. 16(3):409-19
Shimose. R, Matsunga. A, Muro. M. (2011). Effect of Submaximal Isometric Wrist Extension Training on Grip Strength. European Journal of Applied Physiology. 111(3):557-65
Bhardwaj. P, Nayak. S, Kiswar. A, Sabapathy. R. (2011). Effect of static wrist position on grip strength. Indian Journal of Plastic Surgery. 44(1):55-58
Suzuki. T, Kunishi. T, Kakizaki. J, Iwakura. J, Takahashi. J, Kuniyoshi. K. (2012). Wrist Extension Strength Required for Power grip: a Study Using a Radial Nerve Block Model. Journal Hand Surgery Europe. 37(5):432-5
Johnson. J, Bobich, L, Santello. M. (2010). Coordination of intrinsic and extrinsic muscle activity as a function of wrist joint angle during two-digit grasping. Neuroscience Letters. 474(2):104-8