Understanding Skeletal Muscle Function and Grip Strength

Introduction

The skeletal muscle of a human being is made up of individual muscle fibres that enable the muscle to contract or relax depending on the stimuli present. Depending on the stimulus, the individual muscle fibres will respond with an all or none response. This means that individual muscle fibres will either contract to its maximum potential or not at all (Klein, 2007). In order for a subsequent contraction to occur, the muscle must relax first. For students studying physiology or related fields, understanding these muscle dynamics is crucial, especially when exploring topics like psychology dissertation help that delve into human movement and behavior.

The grip strength of an individual is a measure of muscular strength or the maximum force (tension) generated by the muscles in an individual’s hand (Abe & Leoenneke, 2015). The measurements attained from grip strength can be used as screening for the upper body strength and overall strength of an individual. However, this measurement is significant when multiple measurements are taken over period of time (Seethamma, et al., 2019) Since the majority of sporting activities require an individual to have strong concentric contractions of flexor muscles located in their forearms and hands. It is observed that hand grip strength is one of the stronger predictors for general body strength (Seethamma, et al., 2019).

Muscle fatigue is one the factors that affect grip strength, it tends to occurs as result of prolonged or repetitive use of the particular muscle. Individuals who experience fatigue will observe weakness and discomfort. The mechanism of fatigue is multifactorial, it involves the central nervous system, peripheral nervous system, muscle units and individual muscle fibres. At the level of muscle cells, depletion of energy stores may be important (Kinet, 2013). Consequently regular exercise improves muscular function and delays thus reducing fatigue. This means that the amount of work done as well as the duration will be increased.

Studies have shown that that prenatal testosterone may lead to the development of hand preference and cerebral functional asymmetry in humans. Also, low prenatal testosterone levels may lead to the development of left-handedness and the reduced functional asymmetry in males. (Abe & Leoenneke, 2015)

The aim of this experiment is to investigate the relationship between hand grip strength dominance and the forearm size. As well as how does the gender of an individual affect dominance.

The hypothesis is that, the greater the cross –sectional area of the muscle the great the force produced.

Method

In the experiment the grip strength of 22 participants (12 male and 10 female) was measured.

First, the participant’s dominant and non-dominant hand were identified. Then a grip dynamometer was used to measure the grip strength. The participant was asked to hold the dynamometer with their arm hanging by their side while standing up. They were then required to squeeze the dynamometer as hard as possible, while ensuring that their arm was still kept by their side. The process was repeated 3 times for the dominant arm and 3 times for the non-dominant arm, after which the highest of the 3 values was record for each arm.

Furthermore, Eureka cans were used to measure the forearm volume. An elastic band was placed around the wrist and around the elbow of both arms. The participant was then asked to insert their hand slowly into the water until the point where the water reached the first elastic band. The displaced water was then discarded. The participant was asked to gently insert their forearm into the water until the point where the water reached the second elastic. After which the volume of water displaced was measured. The same process was repeated for the other arm and the results were record. Also, the length of the forearm was attained by measuring the distance between the two elastic bands.

To conclude, the volume of fat in the forearm was estimated using the skinfold measurement of the bicep. Skinfold callipers were used to measure a skinfold at the midpoint of the bicep. This was done 3 times for the non-dominant and dominant hand arm, and the observations made were recorded.

Results

From the above graph it can be seen that the grip strength in the dominant hand was greater in the male participants (M=44, SD=9.9) as compared to the female participants (M=28, SD=5.4). In the non-dominant hand the male participant (M=41.6, SD=9.3) had a higher grip strength compared to the female participants (M=26.2, SD=6.2) There was a small difference in the grip strength recorded for the dominant and the non-dominant hand.

From the above graph it can be seen that the dominant hand cross-sectional area for the male participants (M=36.5, SD=9) demonstrated a greater cross- sectional area as compared to the female participants (M=22.5, SD=6.3). Similarly, the non-dominant hand cross-sectional area for the male participants (M=34.2, SD=9.3) demonstrated a greater cross- sectional area as compared to the female participants (M=20.9, SD=5.7). Also, there is a small difference in the cross-sectional are recorded for the dominant and the non-dominant hand in both the male and female participants.

Discussion

The measurement of hand grip strength is one of the methods used to assess for upper extremity muscle strength, it can also be used as a measure for sport performance. Hand grip strength is considered a heritable, indicator of health status, overall masculinity, and reproductive fitness with a substantial genetic component. The experiment was designed to identify the effects of gender and handedness during talent as well as the grip strength that is associated with each gender. The grip strength of an individual depends on the interaction between the synergistic forearm flexor and extensor muscle action. The forearm muscles are primarily in control of the movement of the forearm and hand.

In both the dominant and non-dominant handedness, in both the gender groups, it was found dominant grip strength was greater than non-dominant strength except in male non-dominant. The findings were in line with the literature regarding right-hand grip strength and the strength difference between the two hands, but not with the results for left-hand grip strength (Kinet, 2013). While no significant difference was observed between dominant and non-dominant in the mean hand grip strength, the mean dominant and non-dominant was significantly higher than that of right-handers in the experiment

Furthermore, there are many reasons as to why there is a difference in male hand grip strength and female hand grip strength. Looking at the male anatomy as compared to the female anatomy, it can be seen that males have wider and broader hands while females have much smaller hands. This characteristics give males a bigger advantage when it comes to observing grip strength. Also, another advantage that the males have the females is that they have a greater muscle as compared to the females. Studies have shown that testosterone is important in the development of muscles and that men have more testosterone as compared to women (who have more oestrogen).

There was no significant difference in the mean of the dominant grip strength between dominant and non-dominant females and males. The dominant grip strength was only differentiated in dominant against dominant males, but that moderate difference is likely due to low prenatal testosterone levels. In consistency with the hand grip strength symmetry of male non-dominant the possible explanation of these differences, is that the low prenatal testosterone levels may contribute to the development of left-handedness and reduced functional asymmetry in males (Klein, 2007).

It has been observed that the dominant hand has approximately 10%, on average greater hand grip strength as compared with the non-dominant hand. Moreover, forearm muscle size may strongly contribute to hand grip strength dominance. The increased muscle size in the dominant hand may occur due to muscle contractions during asymmetric hand motion activities such as carrying a heavy load with one hand, throwing a ball, or playing a racket sport.

From the above results, it is evident that there is a direct correlation between cross-sectional area and hand grip strength (both in the dominant and non-dominant hand).

Conclusion

In conclusion, there is a small difference between the dominant and the non-dominant hand in both males and females. However, the dominant is always stronger than the non-dominant hand because of the increase in muscle size due to muscle contractions during asymmetric hand motion activities such as carrying a heavy load with one hand (often the dominant hand).

Moreover, women tend to show a weaker grip strength as compared to their male counterparts. The difference is great and is also observed in the measure of cross-sectional area. Consequently, the hand grip is directly related to the cross-sectional area irrespective of the gender of the individual. The bigger the cross-sectional area the greater the grip strength.

References

Abe, T. & Leoenneke, J. P., 2015. Handgrip strength dominance is associated with difference in forearm muscle size. Journal of Physical Therapy Science , 27(7), pp. 2147-2149.

Kinet, J. H., 2013. The Effect of Upper Extremity Fatigue on Grip Strength and Passing Accuracy in Junior Basketball Players. Journal of Himan Kinetics, Volume 37, pp. 71-79.

Klein, J. L., 2007. Evaluation of the Hand and Upper Extremity. In: C. Cooper, ed. Fundamentals of Hand Therapy; Clincal Reasoning and Treatment Guildlines for Common Diagnoses of the Upper Extremity. Arizona: Elsevier, pp. 73-97.

Seethamma, K. M., Raj, J. O., Prakash, N. & Shetty, K., 2019. Correlation of Forearm Circumference and Hand Length with Grip Strength in. Acta Scientific Orthopaedics, 2(10).

Continue your journey with our comprehensive guide to Understanding Psychological Contracts.