Short-Term Effects of Running Exercise on Pinch Strength, Grip Strength, and Manual Dexterity of the Dominant and Non-Dominant Hands

Introduction

Occupations such as paramedic, police, firefighter, and military require manual lifting tasks and carrying of gear loads.^1–4 Such occupations may demand exertional movement while carrying equipment load, followed by use of the hand and finger muscles. Pinch strength, grip strength, and dexterity of the fingers are important to completion of tasks that require quick and accurate maneuvering of medical instruments, tools, and weaponry.^3,5 Bouts of exercise could affect pinch strength, grip strength, and manual dexterity in the short-term and consequently affect manual task performance on the dominant and non-dominant hands.

Physically-demanding aerobic exercise has been shown to affect muscle force production and force steadiness.^6,7 As muscle force is affected by mechanically demanding or metabolically demanding exercise⁷, the systemic effects from exercise may cause changes to force production needed for manual tasks. For example, all-out cycling bouts in healthy active participants have been shown to result in a prolonged force reduction in the quadriceps muscle when the muscle is stimulated by direct electrical stimulation.⁷ Other exercise, such as short duration maximum voluntary contractions, demonstrated an initial force recovery to pre-exercise values followed by a subsequent force depression in the quadriceps muscle.⁷ However, voluntary activation of muscle, which is representative of use of the hands in a job setting, could produce differing results as compared to electrical stimulation of muscle after exercise. It is also possible that the dominant and non-dominant hands may be affected differently by exercise. Further, it is unknown if whole-body aerobic exercise, that does not require use of the hand and finger muscles, may affect upper limb muscle function.

Level of physical exertion can increase when an individual is carrying a gear or backpack load.^8–11 Previous research has investigated whether walking with a loaded backpack may affect grip strength, pinch strength, and manual dexterity.⁸ When carrying a backpack load, compression of blood vessels and the brachial plexus nerves by backpack straps may affect strength and dexterity of the hands. In a study by Hein et al.⁸, grip strength and manual dexterity measurements were not significantly different after walking with a heavy backpack in a cohort of male participants; however, increases in pinch strength occurred after a seated recovery period. Previously reported measures of hand strength and dexterity after load carriage involve backpack straps that impinge the muscles and nerves of the upper limb. Therefore, these studies do not adequately address whether physical exertion that raises heart rate in and of itself can affect pinch strength, grip strength, and manual dexterity. Further, while normative data have been presented for pinch strength,^12,13 pinch strength has not yet been comprehensively assessed before and after exercise. Therefore, it is relatively unknown if pinch strength may be affected by exercise outside of clinical populations.^14,15 Both grip and pinch strength are important to manual tasks needed for some occupations.^13,15 Grip strength has been widely used for biomechanical assessment in ergonomics, neuromuscular disorders, and as a general measure of overall muscle strength.^16–20 Factors such as age, sex, and dominant hand affect grip strength.²¹ Additionally, hand use and occupational tasks can potentially affect grip strength.²² For example, grip strength in a group of male participants decreased by 20% compared to pre-exercise values after participants walked while carrying a stretcher, and grip strength did not recover after 24 hours.²³ Grip strength has also been shown to decrease over 15% after three stretcher carrying tasks when compared to their pre-exercise values, with the decline in strength being similar in both hands.² Increased characterization of the effects of exercise alone, without placing force on the hands, will provide a foundation to understand hand use after exertion in male and female participants as a better comparison than grip strength, pinch strength, and manual dexterity measures taken at rest.

Manual dexterity skills involving use of the fingers to manipulate objects are important in occupational tasks and are often used to determine neuromotor function. Similar to hand and finger strength measures, manual dexterity can be affected by factors including age and hand dominance.²⁴ Younger persons generally demonstrate faster dexterity completion times than older adults.²⁴ However, Sahin et al.²⁴ demonstrated that the dominant hand is significantly faster than non-dominant hand for a functional dexterity test across age groups. Manual dexterity and its relation to exercise has been researched in populations with neurodegenerative disorders. In a study by Jansen et al.,²⁵ an 8-week high-intensity aerobic exercise intervention improved bimanual motor control and dexterity in persons with Parkinson’s disease. However, research on the effects of exercise on manual dexterity in young adults is limited. It is also unknown how manual dexterity on the dominant and non-dominant hand may be affected in the short term by exercise or exercise with load. Therefore, investigating short-term changes in pinch strength, grip strength and manual dexterity is important to assess potential changes in the ability to perform manual tasks for those in occupations requiring manual strength and dexterity after exercising with load.

Quantitative measures of hand strength and dexterity in male and female participants will add to the current understanding of how these measures may be affected immediately after exercise and exercise with load. The purpose of this study was to examine the short-term changes in pinch strength, grip strength, and manual dexterity after unloaded and loaded running for both the dominant and non-dominant hands. Additionally, the goal was to characterize the effects of exertion alone on hand function, without the confounding effects of shoulder or arm impingement from load applications. We hypothesized that pinch strength, grip strength, and manual dexterity will change after exercise for both the dominant and non-dominant hands. We also hypothesized that changes in pinch strength, grip strength, and manual dexterity will depend on the intensity of exercise.

Materials and Methods

Twenty-four male (mean ± SD of 25 ± 4.0 yrs; 177.6 ± 16.0 cm height; 86.3 ± 9.3 kg mass; 22 right hand dominant) and 10 female (25 ± 6.0 yrs; 165.1 ± 5.1 cm height; 62.1 ± 5.9 kg mass; 9 right hand dominant) individuals participated in the study. Participants were recruited as a convenience sample from a local area. All forms and protocols received ethical approval by the Institutional Review Board at California State University San Marcos (IRB#1756136–1). All participants provided informed written consent. Participants reported being physically active and running at least 2 times per week. Volunteers were screened with a health history questionnaire and an American Heart Association cardiovascular health questionnaire to determine eligibility. The health history questionnaire included questions to evaluate whether participants may need to be excluded for heart disease, gait disorder, recent lower extremity injury, recent concussion, neurological disorder/disease, and recent upper extremity musculoskeletal injuries or surgeries of the wrist or hand. No volunteers were excluded from the study. Statistical software G*Power Analysis (Universitat Keil, Germany) was used to determine that 24 participants were needed to power repeated measures ANOVA for the study with a small effect size and level of significance of p<0.05. Grip strength comparisons were expected to have a small effect size, while pinch strength and manual dexterity were expected to have medium effect size. Participants were given an opportunity to voluntarily provide information on their race and ethnicity. Of the 34 participants, 22 self-reported their race as White, 7 as more than one race, 1 as African American, 2 as Native American, and 2 as Asian. Of the 34 participants, 24 self-reported their ethnicity as non-Hispanic, 4 as Hispanic, and 6 did not specify. Self-reported occupations of the 24 male participants were 5 active-duty military, 1 fire technician, 5 food service workers, 4 students, 3 fitness instructors, 2 construction workers, 1 mechanic, 1 certified nursing assistant, 1 university faculty, and 1 office worker. The 10 female participants had occupations reported as 3 food service workers, 3 students, 2 fitness instructors, 1 traffic controller, and 1 medical laboratory technician. Participants were instructed to wear athletic attire and running footwear.

Participants completed three different exercise conditions: (1) 5-minute seated rest with no exercise (2) run with no load at 3.0 m/s on a treadmill for 5 minutes and (3) run at 3.0 m/s on a treadmill with 9.1 kg evenly distributed around a weighted belt for 5 minutes. In the no-exercise condition, participants remained seated for the 5-minute duration. Five minutes was chosen for the exercise duration as initial protocol testing confirmed 80–90% of estimated maximum heart rate (220 minus age) was achieved in this time span while maintaining the 3.0 m/s velocity. The weighted belt (Pro Weight, Seasoft, Chehalis, WA) was chosen specifically such that load was worn without compression of the upper limb nerves, muscles, or blood supply as compression by straps could impact hand muscle function. The weighted belt was properly fit for each participant. Running while wearing a weighted belt is a scenario similar to what may be experienced by law enforcement officers. The 9.1 kg load was chosen after consultation with a local law enforcement agency to represent the average load worn on a gear belt. A 5-minute seated rest period was provided in between each exercise condition. Participants completed 2 minutes of walking on the treadmill for warm up and were allowed to stretch before running. Participants ran at 3.0 m/s for the running conditions on the treadmill (Bertec, Worthington, OH). The rate of 3.0 m/s was chosen based on previous studies examining running with load in male and female participants^9,26. Order of conditions was randomized for participants. Pinch strength, grip strength, and manual dexterity measurements were taken in that order as quickly as possible beginning immediately after each exercise condition. All measurements were taken with participants standing.

Each participant’s pinch strength was measured for the dominant and non-dominant hand using a pinch dynamometer (Lafayette Instrument Company, Lafayette, IN). Participants were instructed to pinch with maximum effort for 3 seconds using a lateral pinch with the dynamometer between the tip of the 1^st finger and lateral aspect of the proximal interphalangeal joint of the 2^nd finger (Figure 1). Pinch strength was measured immediately after each condition. All trials were performed by alternating between the dominant and non-dominant hand. Participants were given a demonstration on proper pinch positioning and allowed one test pinch strength prior to the first set of measurements, bilaterally.

Grip strength was measured for the dominant and non-dominant hand using a hand grip dynamometer (Lafayette Instrument, Lafayette, IN). The hand grip dynamometer was held by each participant at their side with their elbow in 90 degrees of flexion according to the instructions from the manufacturer (Figure 1). The participant was instructed to squeeze as hard as they could for 3 seconds. Grip strength was measured immediately after each condition. All grip strength measurements were performed by alternating between the dominant and non-dominant hand. Participants were given a demonstration on proper grip positioning and allowed one test grip strength bilaterally prior to beginning any data collection.

Participants also completed a grooved pegboard (Lafayette Instrument, Lafayette, IN) manual dexterity test for the dominant and non-dominant hand. Participants were instructed to stand upright while keeping the hand not in use behind their back. Participants were instructed to pick up one peg at a time and work from left to right on the pegboard when using the left hand and right to left when using the right hand until all 25 pegs were placed (Figure 1). If a participant dropped a peg, they were instructed to leave it and continue with a new peg, and all dropped pegs were documented. Participants were given a demonstration on proper peg placement and allowed a full run-through of the pegboard bilaterally prior to beginning the first set of measurements. Time to complete the pegboard was measured with a stopwatch.

Heart rate was collected for 5 minutes throughout each of the conditions using a Polar Beat heart rate monitor (Polar, Kempele, Finland) that was affixed to a chest strap. The chest strap was properly fitted to each individual. Data was collected using Polar Flow software that was associated to the heart rate monitor.

Microsoft Excel (Microsoft, Redmond, WA) and SPSS (IBM, Armonk, NY) were used to analyze data. Means and standard deviations were computed for all participants’ heart rates, grip strengths, pinch strengths, manual dexterity completion times and number of dropped pegs. Strength and dexterity measures were statistically compared among the no exercise, unloaded run, and loaded run condition using SPSS. Repeated measures analysis of variance (ANOVA) was used to compare among exercise conditions for heart rate, grip strength, and pinch strength. Factorial mixed ANOVA was used for manual dexterity comparisons among exercise conditions and between sexes. If Mauchly’s Test for sphericity was non-significant, we used assumed sphericity for the F and p values, but if it was significant, we reported F and p values with Greenhouse-Geisser correction. Partial eta squared was computed for effect size. Bonferroni post hoc testing was completed. Paired t tests were used for dominant versus non-dominant hand comparisons. Statistical significance was set at p<0.05. We computed the percent difference for statistically significant comparisons and for dominant versus non-dominant hand comparisons. Coefficient of variation (CV) was computed to compare variability in measurements among time points and exercise conditions.

Results

Heart rate was significantly different among the no exercise, unloaded run, and loaded run conditions for male participants (F=343.296, p < 0.001, effect size=0.937) and female participants (F=218.694, p < 0.001, effect size=0.960). Pairwise comparisons demonstrated that the no exercise condition had significantly lower heart rate than the exercise conditions for both male and female individuals (Table 1).

Pinch strength for the dominant hand for male participants was not different after the unloaded run or loaded run when compared to after the no exercise condition (F=0.902, p=0.413; Figure 2). However, for the non-dominant hand, there was a main effect of exercise condition on pinch strength for male participants (F=6.009, p=0.005, effect size=0.207; Figure 2). The unloaded run (p=0.026) and the loaded run (p=0.030) conditions had significantly higher non-dominant hand pinch strength than the no-exercise condition. Measurements of pinch strength for the non-dominant hand in male participants supported our hypothesis that pinch strength would change with exercise, but measurements of pinch strength for the dominant hand did not support our hypothesis (Figure 2). Pinch strength for the non-dominant hand increased on average 7% from no exercise condition to the running conditions. Variability in pinch strength for male participants was consistent for each of the exercise conditions for the dominant hand (CV ranged from 31.0% for unloaded run to 33.2% for loaded run) and non-dominant hand (CV ranged from 30.9% for unloaded run to 33.6% for the no exercise condition). Dominant hand pinch strength was only significantly higher than non-dominant hand pinch strength in the no exercise condition (p=0.022). In male participants, the dominant hand measured 6% stronger for pinch strength than the non-dominant hand for the no exercise condition.

Pinch strength did not change after exercise for female participants for the dominant hand (F=1.338, p=0.287) or for the non-dominant hand (F=0.25, p=0.975). Therefore, measurements in female participants did not support the hypotheses that pinch strength would change after exercise or that changes would depend on the type of exercise. Pinch strength variability for the female participants was similar across all exercise conditions for the dominant hand (CV ranged from 34.1% for the no exercise condition to 38.5% for the unloaded run) and the non-dominant hand (CV ranged from 41.7% for the unloaded run to 43.0% for the no exercise condition). Pinch strength for the dominant hand was significantly greater, by at least 12%, than pinch strength for the non-dominant hand in both the no exercise (p=0.002) and loaded run (p=0.007) conditions for female participants.

Contrary to our hypothesis, grip strength for male participants for the dominant hand did not significantly change after exercise (F=0.677, p=0.513). Grip strength for male participants changed significantly for the non-dominant hand (F=4.147, p=0.035, effect size=0.153, Figure 3), with significant differences computed between the unloaded run and the loaded run (p=0.025). Specifically, average grip strength for male participants for the non-dominant hand was 4% higher when comparing measurements after the loaded run to measurements after the unloaded run condition, but was not different compared to the no exercise condition. Average male non-dominant hand grip strength after the no exercise condition was 49.7 ± 8.3 kg, during unloaded run was 48.0 ± 7.3 kg, and loaded run was 49.7 ± 7.7 kg (Figure 3). Variability in grip strength was consistent for all conditions for the dominant hand (CV ranged from 16.9 % in no exercise condition to 17.4 % in unloaded run). For the non-dominant hand, CV for grip strength was highest for no exercise condition at 16.6% and was lowest for unloaded run at 15.2%. Grip strength for male participants was significantly higher, by 4%, on the dominant hand compared to the non-dominant hand for the unloaded run condition (p=0.013).

For female participants, grip strength did not significantly change after exercise for the dominant (F=0.049, p=0.953) or non-dominant hand (F=0.236, p=0.792), therefore, the data do not support our hypothesis. For female participants, variability in hand grip strength was consistent across all exercise conditions for both the dominant and non-dominant hand with CV ranging from 11.0% for the non-dominant hand in the no exercise condition to 15.0% for the dominant hand in the unloaded run condition. There was no difference between the dominant and non-dominant hand grip strength for female participants for any exercise condition.

Manual dexterity completion times did not significantly change after exercise for the dominant hand (F=1.706, p=0.190) or for the non-dominant hand (F=2.344, p=0.104) for male and female individuals. Between group comparisons demonstrated female participants had significantly faster completion times than male participants for both the dominant (F=4.656, p=0.039, effect size=0.127) and non-dominant hand (F=6.145, p=0.019, effect size=0.161). Dominant hand manual dexterity times were significantly faster than non-dominant hand completion times in all exercise conditions for male participants but not for female participants (Table 2). Some pegs were dropped in all exercise conditions; however, the average peg drop for all conditions was less than one peg as some participants did not drop any pegs. The non-dominant hand after the unloaded run had the highest average dropped pegs for both female and male participants (Table 2). Variability in manual dexterity completion times for the dominant hand for males ranged from a CV of 9.5% to 12.4% across exercise conditions and for the non-dominant hand the CV ranged from 14.4 % to 15.0 %. For female participants, CV for completion times ranged from 10.8% to 17.5% for the dominant hand across exercise conditions and from 5.8% to 14.9% for the non-dominant hand. The non-dominant hand demonstrated higher variability for manual dexterity than the dominant hand in all three exercise conditions for male participants, but not for female participants. These data did not support our hypothesis that manual dexterity times would change with exercise or exercise with load.

Discussion

The aim of this study was to investigate short-term changes in pinch strength, grip strength, and manual dexterity after running without and with load. The findings demonstrated differences between the dominant and non-dominant hands. Measurements from the dominant hand did not support our hypothesis, as the dominant hand maintained both pinch and grip strength after short exercise bouts for both male and female participants. Interestingly, for males, the non-dominant hand strengths were more affected by exercise than the dominant hand. There was an increase in pinch strength after exercise for males. All participants demonstrated higher coefficient of variation for pinch strength than for grip strength, but similar variability in both the no exercise and exercise conditions. Differences in non-dominant hand grip strength for male individuals between running conditions supported the hypothesis that changes in grip strength would depend on intensity of exercise. However, grip strength did not change with exercise for female participants. These findings imply that personnel who use their hands after exertion may maintain grip and pinch strength for their dominant hand, but it is possible that some people could experience changes in force production for the non-dominant hand. Therefore, it might be suggested that immediately after exertion, the dominant hand should be used if task performance requires consistent strength. Additionally, exercise did not substantially affect manual dexterity completion times for a grooved pegboard test for females or males. However, task completion time was longer for the non-dominant hand compared to the dominant hand for males. Female participants showed no difference in completion times between dominant and non-dominant hand, but demonstrated manual dexterity times that were significantly faster than male participants in all exercise conditions for both hands. An implication of these findings is that personnel who perform tasks with medical instruments and small equipment would likely maintain dexterity for both the dominant and non-dominant hands after short bouts of exercise.

Our hypothesis that changes in pinch strength, grip strength, and manual dexterity measurements would depend on the intensity of exercise, specifically whether load was worn while running or not, was only supported by non-dominant hand grip strength measurements in male participants. It was expected that running while wearing a 9.1 kg weighted belt, representative of a law enforcement gear belt, would be a more metabolically demanding exercise than unloaded running. Non-dominant grip strength was significantly different between the unloaded and the loaded run for male participants but did not have any significant differences when compared to the no exercise condition. Specifically, mean grip strength for the non-dominant hand for male participants was lower after the unloaded run condition when compared to grip strength after the loaded run condition. All other measurements did not support our hypothesis that changes in strength and dexterity would depend on whether exercise had increased intensity due to addition of wearing a load.

Skurvydas et al.⁷ provided insight into the effect of exercise on muscle strength using stimulation evoked contractions of the quadriceps muscles after whole body exercise including cycling and drop jumps. Specifically, force was measured in a muscle that underwent contraction, either concentric or eccentric, during the exercise protocol.⁷ Force depression was shown to occur after metabolically demanding exercise or after mechanically demanding quadriceps muscle contractions.⁷ The present study differs from the previous research in that voluntary muscle activation was used and the whole body exercise was not physically demanding to the hand and finger muscles. Hence, the mechanism of a change in strength production would likely be linked to metabolic mechanisms occurring during demanding exercise as the hand and finger muscles were not generating force during the running exercise. When using stimulation of the quadriceps after exercise, none of the exercise conditions resulted in an increase in force post-exercise.⁷ In contrast, an increase in pinch strength for the non-dominant hand was demonstrated in the present study immediately after exercise. As force depression was not seen in grip strength or pinch strength measures immediately after whole body exercise, it is possible that the differences when compared to previous research are related to several factors: differences in voluntary versus stimulation evoked contractions to produce muscle force, there being no mechanical demand of the hand and finger muscles during the actual running exercise, or increased blood flow to the hand and finger muscles contributing to increased force production. However, the findings of this study add to the understanding of strength measures after exercise and are relevant to ergonomic use of the hands in a job setting as the participants used voluntary muscle contractions.

The present study had a loaded run condition that used a belt and did not involve any compression of the brachial plexus and blood vessels of the shoulder. In comparison, after walking with heavy backpack load, quantitative assessment of hand strength and dexterity revealed that pinch strength changed after a seated recovery, but no difference was reported in grip strength immediately after load carriage exercise as compared to before the exercise.⁸ In the Hein et al.⁸ study, upper limb measurements could have been affected by backpack strap compression of the nerves and blood vessels. Despite the differences in how the load was applied, the results were similar in both studies with no change in grip strength and manual dexterity completion times after exertional exercise with load.

The results of the present study compare well to data from similarly aged participants in other studies on pinch strength, grip strength, and manual dexterity. The present findings are consistent with pinch strength published for 96 males aged 23–26 years which averaged 9.2 kg on the dominant hand and 8.7 kg on the non-dominant hand.¹² Maleki-Ghahfaroki et al.¹² reported pinch strength for the dominant hand was 5.3%−7.5% stronger than the dominant hand, with the difference between hands being higher in female participants. Our results show a similar between-hand comparison of 6% difference with greater pinch strength on the dominant hand for male participants and a 12% difference for female participants. For grip strength, Mathiowetz et al.¹³ state that males aged 25–29 had an average right-hand grip strength of 54.8 kg and left-hand grip strength of 50.1 kg. While our results align well with these grip strength values, it should be noted that Mathiowetz et al.¹³ only report by right and left hand and 6 participants out of 27 males were left-handed. Therefore, some differences from the normative data published may be due to not separating out data by dominant hand. Sahin et al.²⁴ presented manual dexterity test completion times and demonstrated that the 20–39 year-old group were 13% faster when completing a functional dexterity test with their dominant hand compared to their non-dominant hand. Although the functional dexterity test involved a turn and place task with 4 pegs, in contrast to the grooved pegboard in the present study, the differences in timing for the dominant and non-dominant hand were similar to the present study with male participants being 7% to 11% faster with their dominant hand dependent on exercise condition.

There were several limitations and assumptions for this study. First, average age of participants was 25 years. Grip and pinch strength decrease with age¹⁹, and therefore the results of this work are applicable to persons of similar age to the present study participants. The participants spanned an 11-year range of ages which allowed us to detect changes due to exertion without the confounding effect of age on pinch and grip strength. The findings are not generalizable to other age groups, as exercise could potentially have a different effect on strength and dexterity in older adults. Also, the participants for this study were untrained and therefore individuals practiced at high dexterity tasks may be affected differently by exertion as specificity of practice has been reported to improve performance in other research.²⁷ It should be noted that the load was not normalized to body weight. The weight belt was on average 15% of body weight for female participants and 11% of body weight for male participants. Additionally, we compared the average, rather than the maximum, of three repetitions for grip strength and pinch strength, as this is more representative of pinch and grip strength in the field for occupational use. Personnel who use pinch and grip strength would not likely use their maximum effort on every repetition during their day-to-day work; hence the averages were used for comparison to represent a person’s ability during repeated manual tasks. It is possible that as a person repeats a task more than 3 times, such as pinch and grip strength measurements, there could be a difference in average strength. It was assumed that fatigability was not a factor when repeating maximal pinch and grip strength evaluations 3 times. Also, it would further the understanding of use of the hands after exercise to explore timing of specific manual tasks used by the military, law enforcement, or first responders in future studies as the grooved peg board provided a standardized test, but isn’t a task completed as part of an occupation. All measurements taken in this study were within 15 minutes after the completion of the exercise. Therefore, the results are only representative of force and dexterity in the hands and fingers immediately after exercise.

In summary, this study compares well to measures reported in previous literature for pinch strength, grip strength and manual dexterity, but adds to the understanding of the possible effects that aerobic exercise has on upper limb function. This research tests a scenario representative of real-life situations such as a police officer or other first responders needing to use their hands after short bouts of running. Five minutes of running exercise resulted in strength changes for the non-dominant hand for grip strength and pinch strength in male participants but did not result in strength changes for the dominant hand in either female or male participants. Additionally, manual dexterity completion times did not change after moderate to vigorous exercise for the dominant or non-dominant hand. Overall, there was no significant loss of strength or dexterity in the hands within the first 15 minutes after exercise. This study elucidates the role of exercise and exercise with a loaded belt on use of the upper limbs without compression of backpack straps. Some measurements of manual function, such as pinch strength, are inherently more variable, and this is a factor that may be worth consideration when looking at ergonomic implications for tasks such as using a syringe or other medical instruments. For example, personnel who utilize both hands for specific tasks may be able to perform tasks with the hands and fingers with more consistent strength if they train and practice with both dominant and non-dominant hands. Therefore, practicing job related tasks after short bouts of exercise could possibly improve overall manual task performance for both dominant and non-dominant hands as previous research has shown physical tasks often adhere to the principle of specificity in which performance can be improved by using conditioning contexts similar to actual task performance.²⁷ In general, grip strength, pinch strength, and manual dexterity completion times remained relatively steady for the dominant hand after short-term exercise in male and female participants. The results of the present study imply that manual strength and dexterity is maintained in the short term for tasks that may involve use of the hands after exercise.