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Resting levels of stress hormones and their association with hand function in young women but not in men
PhD, Rawan A. Alboushi4BSc OT, Sama Alshalawi3BSc OT, Mohammed Salah Alnumani1MBBS, Jawad Alammar1MBBS, Feras Shmeylan Alharbi1MBBS, Fatimah Hulayil Alenazi6BSc OT, Manar Mahaya Almutairi5BSc OT, Thamer Alharbi1MBBS, Khalaf Nahedh Albaqami1MBBS, Moeber Mahzari2,7,8MBBS, MME
*Corresponding author: Awad M. Almuklass, Department of Basic Medical Sciences, King Saud Bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia. muklassa@ksau-hs.edu.sa
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Received: ,
Accepted: ,
How to cite this article: Almuklass AM, Alboushi RA, Alshalawi SA, Alnumani MS, Alammar J, Alharbi FS, et al. Resting levels of stress hormones and their association with hand function in young women but not in men. Int J Health Sci (Qassim). 2025;19(5):19-24. doi: 10.25259/IJHS_9073
Abstract
Objectives:
Manual dexterity is influenced by various physiological and cognitive factors. This study aimed to examine the association between resting salivary cortisol levels, “a biological marker of stress,” and hand function performance.
Methods:
Eighty-three healthy young adults (mean age: 22.8 ± 2.8 years; 40 women) were randomly assigned to two groups: One group (n = 40) underwent testing in the morning only, while the other group (n = 43) underwent both morning and evening assessments. Participants provided saliva samples and completed the Grooved Pegboard Test (GPT), which measures manual dexterity. Spearman’s correlation was used to evaluate associations between cortisol levels and GPT performance.
Results:
The mean GPT completion time was 63.8 ± 8.1 s. Cortisol levels were significantly higher in the morning (0.22 ± 0.12 mg/dL) than in the evening (0.15 ± 0.18 mg/dL). A positive correlation was observed between cortisol levels and GPT completion time across all participants (r = 0.27, P = 0.003). When analyzed by gender, a significant association was found in women (r = 0.39, P = 0.002), but not in men (r = 0.17, P = 0.18).
Conclusion:
Higher resting cortisol levels were associated with slower hand function performance in women, suggesting a gender-specific effect of stress hormone levels on manual dexterity.
Keywords
Cortisol hormone
Grooved pegboard test
Manual dexterity
Stress hormone
INTRODUCTION
Manual dexterity refers to the precise coordination and control of hand and finger movements, enabling individuals to perform complex motor tasks. These fine motor skills are essential for activities requiring precision, such as typing, playing musical instruments, performing surgery, and other skilled hand-based tasks.[1-3] One common method for assessing manual dexterity is the Grooved Pegboard Test (GPT), which evaluates fine motor coordination by testing the interplay of vision, hand movements, and cognitive control. Participants are required to insert small, grooved pegs into corresponding holes on a board, necessitating precision and coordination. Clinically, the GPT is widely used to detect neurological impairments affecting fine motor and cognitive functions.[4-8] Performance variability on the GPT is influenced by multiple factors, including cognitive function, visual acuity, neuromuscular integrity, and aging.
An additional factor influencing hand function performance yet underexplored in this context is psychological stress. Elevated cortisol levels, a physiological marker of stress,[9] have been linked to changes in both cognitive and motor domains. These changes may manifest as reduced attention span, increased muscle tone, and impaired motor precision, all of which can interfere with the accuracy and steadiness required for fine motor tasks.[10-14] Furthermore, anxiety associated with elevated cortisol can produce tremors and impair motor accuracy. Chronic cortisol elevation has also been linked to declines in cognitive control, memory, and decision-making, potentially compounding deficits in manual dexterity.[15-17]
Based on this evidence, we hypothesized that individuals with elevated resting cortisol levels would exhibit reduced performance on the GPT. Moreover, we anticipated that this relationship might differ by gender, given prior findings of sex-based differences in stress response and motor behavior.
Previous studies have directly exposed participants to stressors during hand function tasks, showing that stress-induced arousal can disrupt muscle strength and coordination.[18-21]
However, the relationship between resting cortisol levels and manual dexterity remains less well-defined. This study aims to examine this relationship using the GPT, providing insight into whether baseline cortisol concentration, “a marker of physiological stress” may influence fine motor performance in healthy young adults.
MATERIALS AND METHODS
Eighty-three young adults (mean age: 22.8 ± 2.8 years; 40 women) participated in the study [Table 1]. The inclusion criteria required participants to be healthy, right-handed men and women aged 18-34 years. Exclusion criteria were applied through a standardized screening form to eliminate individuals with conditions potentially impacting manual dexterity, performance, or resting cortisol levels.
| Parameter | |
|---|---|
| Age, years (Mean±SD) | 22.8±2.8 |
| Gender, n(%) | |
| Men | 43 (52%) |
| Women | 40 (48%) |
| Height, cm (Mean±SD) | 166.2±8.6 |
| Weight, kg (Mean±SD) | 67.9±12.97 |
SD: Standard deviation
Specifically, the exclusion criteria included vision disorders; impaired senses of smell or taste; dysfunctions involving tongue or lip movement; speech difficulties; untreated hearing impairments; sensory disturbances in the face, head, or neck; reduced muscle strength or tone (particularly in the upper extremities); loss of sensations such as temperature, pressure, or pain; impaired body or limb position perception; coordination deficits; hormonal or endocrine disorders (including cortisol-related conditions); and a history of stroke, diabetes, severe head injury, or seizures.
Participants were also excluded if they used antidepressants, anticholinergics, stimulants, sedatives, neurologic pain medications, seizure medications, cannabis, illicit drugs, or painkillers. Additional exclusions included taking supplements (e.g., steroids, magnesium, omega-3), having shoulder, hand, or wrist issues affecting functional abilities, or consuming a meal within the hour before participation.
Study design and settings
This study incorporates two primary measurements: The Grooved Pegboard Test (GPT) and cortisol levels obtained from saliva samples. Due to the inherent variability in these measures within the population, the standard method for sample size calculation (e.g., G-power) was not applied. Instead, the sample size was guided by previous studies with comparable designs that reported statistically significant findings using sample sizes ranging from 30 to 70 participants.[4,15,16] While no formal power analysis was conducted, our sample size of 83 exceeds the upper range of prior studies, supporting the adequacy of statistical power for detecting meaningful effects. Nonetheless, this is acknowledged as a limitation and recommended that future studies perform power analyses tailored to specific effect sizes of interest.
An observational study with randomized assignment to different data collection time points was conducted at the College of Medicine, King Saud bin Abdulaziz University for Health Sciences. Participants were randomly assigned to one of two groups using a computer-generated randomization list created in advance by one researcher. Group assignments were concealed in sealed files and opened sequentially after participant enrollment. In group A (n = 40), the Grooved Pegboard Test (GPT) was administered, and a single saliva sample was collected at approximately 8:00 AM. In group B (n = 43), the same procedure was followed; however, saliva samples were collected at two-time points: ~8:00 AM and ~5:00 PM. The GPT was used to evaluate manual dexterity, while the saliva samples were analyzed to measure cortisol levels.
Data collection process
Each participant completed a screening form and a consent form before being briefed on the study procedures and signing their agreement to participate. In addition, participants completed the Edinburgh Handedness Test, a validated questionnaire designed to determine handedness and differentiate between left- and right-handed individuals.[22] After completing the forms, participants were randomly assigned to one of two groups in a 1:1 ratio and assigned a unique identification number for tracking throughout the study.
Participants were directed to either the Grooved Pegboard Testing (GPT) station or the saliva collection station, with the order of these tasks counterbalanced among subjects. The GPT involves a board with 25 slots, each oriented differently, and 25 corresponding pegs. Participants were provided clear instructions before starting and were asked to complete the test using their dominant hand. According to the GPT manual, participants were required to use their right hand to fill the slots from left to right and bottom to top as quickly as possible and vice versa. Before the official test, participants were allowed to practice by filling the first row of the board to familiarize themselves with the procedure. The time taken to complete the test was recorded using a stopwatch.
For saliva collection, participants were instructed to first gather saliva at the bottom of their mouth and then transfer it into a designated measuring tube. The collected samples were securely sealed, labeled, and coded with each participant’s unique identification number. Samples were organized on racks according to the participant’s assigned group. Immediately after labeling, the saliva samples were transported to the laboratory, frozen at or below −20°C, and stored. Cortisol levels in the saliva were later analyzed using the Salimetrics® Cortisol Enzyme Immunoassay Kit (Salimetrics, LLC, USA) following the manufacturer’s guidelines.
Data analysis
Participant confidentiality was maintained by coding the data during analysis. The normality of the data was assessed using the Shapiro-Wilk test, with P > 0.05 indicating a normal distribution. Statistical tests were selected based on the results of the normality test. For within-group comparisons, the paired t-test was applied to normally distributed data, while the Wilcoxon test was used for non-normally distributed data. For between-group comparisons, an independent-samples t-test was used for normally distributed data, and the Mann-Whitney U-test was employed for non-normally distributed data. Associations were evaluated using Spearman’s rho correlation, with the correlation coefficient reported. To minimize Type I error, P < 0.025 was considered statistically significant. Cohen’s d effect size was calculated to assess differences between male and female participants as well as between AM and PM results. All statistical analyses were conducted using IBM Statistical Package for the Social Sciences Statistics, version 25.
Cortisol levels were quantified in saliva samples using the Salimetrics® Cortisol Enzyme Immunoassay Kit (Salimetrics, LLC, USA) following the manufacturer’s protocol. Saliva samples were centrifuged at 1500 × g for 15 min. Subsequently, 50 mL of controls, standards, and saliva samples were added to designated wells on a 96-well plate pre-coated with anti-cortisol antibody. The enzyme conjugate was diluted to a 1:1600 ratio, and 200 ml of the solution was added to each well. The plate was mixed at 500 rpm and incubated at room temperature for 1 h. After incubation, the plate was washed four times with a 1× wash buffer. Next, 200 mL of tetramethylbenzidine (TMB) substrate solution was added to each well, mixed at 500 rpm for 5 min, and incubated in the dark for 25 min. Finally, 50 mL of stop solution was added to each well, mixed at 500 rpm for 3 min, and the plate was read at a wavelength of 450 nm. Cortisol concentrations were expressed in mg/dL and determined using a 4-parameter non-linear regression curve.
To further reduce bias, investigators who conducted the GPT were not involved in the cortisol analyses, and vice versa. In addition, the order of saliva collection and GPT testing was counterbalanced across participants.
RESULTS
A total of 83 participants were included in the study [Table 1]. In terms of GPT performance, females were faster than male participants, with an average time of 61.2 ± 7.3 s, whereas males took an average of 66.1 ± 8.1 s (P < 0.001, effect size = −0.64) [Table 2]. The difference in cortisol levels was not statistically significant between female and male participants except when measured in the evening. Female participants had higher cortisol levels = 0.21 ± 0.24 mg/dL than male participants = 0.10 ± 0.05 mg/dL (P = 0.017, effect size = 0.63) [Table 2].
| Men (n=43) | Women (n=40) | P-value | Effect size (Cohen’s d) | |
|---|---|---|---|---|
| EHI score | 389.5±25.7 | 390±30.4 | 0.66 | 0.018 |
| GPTa (s) | 67.0±7.7 | 62.0±7.9 | 0.002 | −0.64 |
| GPTp (s) | 64.3±8.8 | 59.8±5.7 | 0.09 | −0.62 |
| Total GPT (s) | 66.1±8.1 | 61.2±7.3 | <0.001 | −0.64 |
| Salivary cortisol (AM) µg/dL | 0.22±0.14 | 0.20±0.10 | 0.152 | −0.16 |
| Salivary cortisol (PM) µg/dL | 0.10±0.05* | 0.21±0.24 | 0.017 | 0.63 |
| Salivary cortisol (Total) µg/dL | 0.19±0.13 | 0.2±0.16 | 0.743 | 0.07 |
EHI: Edinburgh Handedness Inventory. *P-value of PM cortisol compared to AM cortisol in the men patient is <0.001. GPTa: Grooved Pegboard Test at morning. GPTp: Grooved Pegboard Test at evening
Time influences cortisol levels and GPT. Cortisol levels were significantly higher in the morning than in the evening. Statistical tests were performed within subjects in group B and between subjects in group A (morning only) and group B (evening only) [Figure 1]. Within subjects’ analyses showed that cortisol levels were higher in the morning (0.20 ± 0.12 mg/dL) than in the evening (0.15 ± 0.17 mg/dL) (P = 0.022, effect size = 0.34) [Figure 1 and Table 2]. Between subjects, analyses revealed that morning cortisol levels were higher (0.24 ± 0.12 mg/dL) than evening levels (0.15 ± 0.17 mg/dL) (P < 0.001, effect size = 0.61) [Figure 1]. After stratification of the data for men and women, it is only the men who showed a reduction in cortisol levels in the evening (P < 0.001, effect size = 1.1) [Table 2].
- Group allocation and comparison of morning vs. evening cortisol levels and cortisol levels results among groups. It shows mean cortisol concentrations (µg/dL) in the morning (group A, n = 40) and morning-and-evening (group B, n = 43). *P value = 0.022 within group comparison (am vs. pm). **P value = <0.001 between groups comparison, morning (group A) vs. evening (group B).
Cortisol levels and gender differences
The results indicate that females had significantly higher cortisol levels in the evening (0.21 ± 0.24 mg/dL) compared to males (0.10 ± 0.05 mg/dL, P = 0.017).
This aligns with the Spearman’s rho correlation showing that the relationship between cortisol levels and pegboard test performance (time) was significant for females (r = 0.39, P = 0.002), but not for males (r = 0.17, P = 0.18). The higher cortisol levels in females may explain the stronger correlation between cortisol and pegboard performance in this group.
Cortisol levels and pegboard test performance
The overall Spearman’s rho correlation (r = 0.27, P = 0.003) indicates that higher cortisol levels are associated with slower performance on the Grooved Pegboard Test (GPT) for all participants. This is consistent with the significant difference in GPT time between men and women [Table 2], where women had better performance overall, likely due to differences in the cortisol impact.
Time influence
Both datasets highlight the influence of cortisol levels at specific times. The results shows significant differences in cortisol levels between the morning and evening (e.g., in Group B, AM vs. PM cortisol, P = 0.022), while the Spearman’s rho findings demonstrate how these cortisol fluctuations correlate with motor performance.
DISCUSSION
This study investigated the relationship between manual dexterity, measured through the Grooved Pegboard Test (GPT), and resting cortisol levels in 83 young men and women. The research was based on two main ideas. First, resting cortisol levels may influence decision-making strategies, as shown by Van Den Bos et al.,[15] who found that changes in cortisol levels affected decision-making and performance differently in men and women. In addition, their study noted that behavioral responses evolved over time, highlighting gender differences. Second, decision strategies may impact GPT performance, as Almuklass et al.[16] demonstrated. Their research showed that participants with faster GPT times tended to prioritize speed over accuracy, resulting in poorer steadiness during force-matching tasks, linking cognitive strategies to motor task performance.[16]
Cortisol levels were found to be higher in male participants during the morning compared to the evening. However, female participants did not show a significant difference in average resting cortisol levels between the morning and evening. These findings align with existing evidence suggesting differences in cortisol levels and stress responses between men and women.[23] Previous research has indicated that women generally exhibit higher resting salivary cortisol levels compared to men.[24] In addition, women have been observed to display elevated cortisol levels during stress-inducing situations, such as aggressive play, compared to men.[25]
In this study, female participants had higher cortisol levels in the evening compared to male participants, although no significant differences were observed in the morning. This pattern may reflect variations in the circadian rhythm of cortisol secretion, which typically decreases at night and increases in the morning. However, the timing, rhythm, and amplitude of cortisol secretion are known to differ by gender,[26] which could explain the observed disparities. These findings suggest that the timing and regulation of cortisol secretion may influence hormonal and stress responses differently in men and women. The findings suggest that the female participants in the study may not have experienced a decrease in cortisol secretion by the time the second sample was collected. In this study, resting salivary cortisol levels were positively correlated with the time it took women to complete the standard manual dexterity test (Grooved Pegboard Test), whereas no significant correlation was observed in men. This aligns with previous research, where women generally performed faster than men on the GPT, regardless of the time of day. This indicates that stress hormones may have a gender-specific influence on hand function performance, with women exhibiting poorer performance on the GPT when cortisol levels are higher. The present study highlights an additional factor influencing hand function in healthy young adults assessed through the GPT. However, the impact of resting cortisol levels on hand function seems minimal in young adults and may diminish with age, at which point other factors like neuromuscular integrity and cognitive function likely take precedence.[4-7,27]
Despite the strengths of this study in highlighting gender-specific associations between cortisol levels and manual dexterity, several limitations should be acknowledged. First, the sample was limited to healthy, right-handed young adults, which restricts the generalizability of the findings to broader populations, including older adults, left-handed individuals, or those with underlying health conditions. Second, although randomization was used to assign participants to different measurement schedules, the study design remains observational in nature and does not allow for causal inferences or longitudinal tracking of hormonal fluctuations over time. In addition, while the stratification by gender adds value, the absence of a formal sample size calculation using standard tools such as G-Power, may affect the statistical power and generalizability of the findings within each subgroup and may not have been large enough to detect subtler associations, particularly in men. Finally, the absence of psychological stress assessments limits the interpretation of cortisol reactivity in a real-life stress context. Future studies are encouraged to adopt a longitudinal design, expand participant diversity, and incorporate additional biological and behavioral stress indicators. Exploring the interplay between cortisol and sex hormones, as well as their combined impact on motor control, would further advance our understanding of neuroendocrine influences on hand function.
CONCLUSION
Resting salivary cortisol levels, a key stress hormone, were positively correlated with the time it took women to complete a standard manual dexterity test (grooved pegboard test), whereas no significant correlation was found in men. This study underscores the influence of resting cortisol levels on fine motor skills and highlights gender differences in hand function. These differences may stem from variations in stress hormone levels and the distinct ways in which males and females respond to stress.
Acknowledgment:
We acknowledge the support of the Research Office at King Saud bin Abdulaziz University for Health Sciences, and Ms. Atika Al Sudairy for her assistance with the copy-editing phase. We also acknowledge Mr. Ahmed Abu Jaffal, Laboratory Technologist, for his technical support and expertise in the analysis of salivary cortisol samples.
Ethical approval:
The Institutional Review Board ethical approval was obtained from King Abdullah International Medical Research Center, Ministry of National Guard-Health Affairs (No. SP18/444/R), dated January 1, 2019.
Declaration of participant consent:
The authors certify that they have obtained all appropriate participant consent.
Conflicts of interest:
There are no conflicts of interest.
Availability of data and material:
The datasets used and/or analyzed during the present study are available from the corresponding author on reasonable request.
Financial support and sponsorship: This study did receive a grant from King Abdullah International Medical Research Center, Riyadh, Saudi Arabia (Protocol number. SP18/444/R. Memo No. RYD-19-417780-44963).
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