# Handgrip Strength as an Indicator of Overall Strength and Functional Performance--Systematic Review
## 3 Results
### Dependence Between Hand Grip Strength and the Values of the Moments of Muscle Forces in Upper limbs  
The authors sought dependences between hand grip strength and the moments of muscle forces in upper limbs [23; 29; 30; 31; 32; 33]. The tests were performed in various positions: in a sitting position with an elbow flexed [23; 30; 33] or extended [31], in a standing position with an upper limb hanging by the side of the body [29; 32], and an upper limb elevated [29]. In their research, the authors took into consideration different groups of individuals. The dependences between hand grip strength and muscle strength were sought after, for instance, in a group of patients with chronic hemiparesi due to stroke [30], healthy athletes [29], volleyball players of the national representation of Brazil [23], people with shoulder pain, weakness, MRI-confirmed RC tears [31] and patients with spinal cord injury, with the time since the injury of at least 6 months [33]. The tests also included healthy individuals, both at a young and elderly ages [32]. [PERSON] et al. [29] checked at which position of the upper limb, during the measurement of hand grip strength, the highest values of correlation with the moments of muscle forces were achieved in the joints of upper limbs. They also investigated which value obtained from the measurements, the mean value of the highest moments of muscle forces or the value of the highest single moment, was more strongly correlated with the values of hand grip strength. The results of their research showed that the highest values of the Pearson correlation were reached when the correlation was performed between the mean values of the moments of muscle forces and hand grip strength when the elbow was flexed at an angle of 90 degrees. This position produced correlation coefficient R for the limbs dominating in the range from 0.42 to 0.71 in the case of shoulder abductors, from0.45 to 0.66 in the case of elbow flexors, and from 0.4 to 0.54 in the case of shoulder rotators. The results of the correlation were statistically significant (\(p<0.05\)), except for the results obtained in the case of internal rotators of the shoulder. The authors ascertained that hand grip strength could be used as a strength indicator of shoulder stabilizers (with a certain caution). [PERSON] et al. (2020) also pointed out that hand grip strength is linearly correlated with the values of force moments of internal and external rotators of the shoulder measured in isokinetic conditions (R from 0.23 to 0.72). It was also confirmed by [PERSON] et al. (2019) by obtaining higher values of the Pearson correlation, i.e., from 0.6 to 0.82 (all results statistically significant \(p<0.05\)). On the basis of this range, authors came to the conclusion that in the case of a lack of isokinetic dynamometers, the measurement of hand grip strength could be used to monitor the strength of stabilizers. [PERSON] et al. (2019), on the basis of analyses, obtained the Pearson correlation values for abductors amounting to 0.378, whereas the value of the rotator cuff (RC) was slightly higher and amounted to 0.421. The authors drew attention to a weak linear correlation between the loss of hand grip strength and abduction strength (r = 0.27), and RC (r = 0.193). No dependences were found between hand grip strength and the rotator cuff dysfunction. The researchers assessed that hand grip strength should not be used solely for the diagnosis of the RC injuries. On the basis of the conducted tests, [PERSON] et al. (2020) pointed out changes in the muscle strength values of upper and lower limbs occurring with increasing age in a group of men and women. The values of the Pearson correlation obtained by the researchers between hand grip strength and the values of muscle force moments equaled 0.3-0.6 in the case of women and 0.35-0.65 in the case of men (all coefficients were statistically significant \(p<0.01\)). The researchers found that in most cases, hand grip strength was weakly correlated with the moments of forces in upper and lower limbs.