Measuring the Effects of High Intensity, Short Duration Upper Body Exercise: An Assessment of Fatigue on Grip Strength in Dominant Arms with a Hand Dynamometer & Electromyography

1. Measuring the Effects of High Intensity, Short
Duration Upper Body Exercise:
An Assessment of Fatigue on Grip Strength in
Dominant Arms with a Hand Dynamometer &
Electromyography
Gayane Balasanyan
Belinda Calderon
Alannah Moises
San Francisco State University 1

2. Introduction & Significance
Grip strength:
● a good indicator of overall
health and vitality
(Poitras 2011)
● essential for strength
development & injury
prevention
● reflective of muscle mass
● used as a precursor to
future health related
complications (Shea 2007)
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3. Research Question
What effect does fatigue from exercise have
on hand grip strength between male and
female subjects?
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4. Physiology - Muscles Used in Gripping
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5. Physiology
● Action potential moves down
sarcoplasmic membrane and
T-tubules activating the release
of Calcium ions into the cell
● Calcium ions bind to troponin
which shifts & exposes myosin
binding sites on actin
● Breakdown of ATP activates
myosin crossbridges producing a
power stroke
○ Thin filament (actin) slides
past the thick filament
(myosin)
○ Sarcomere shortens, the
muscle contracts
● EMG values are indicative of
muscle activity
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6. Physiology
When moving from rest to high-intensity exercise:
● energy consumption in skeletal muscle cells
rapidly increases
● anaerobic metabolism provides most of the
required ATP
● Skeletal muscle becomes fatigued — a rapid
decline in contractile function (Westerbald et al 2006)
Bicep curls stimulate isotonic muscle contraction —
muscles contract and shorten
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7. Physiology - High Intensity, Short Duration Exercise
● Reliance on fast-glycolytic fibers
○ Large in diameter
● Training increases strength
○ Muscle fibers get larger
○ increased glycogen stores
○ increased glycolytic enzymes
○ Fast-oxidative-glycolytic
fibers converted to
fast-glycolytic fibers
○ Fatigue easily
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8. Physiology - Muscle Fatigue
Muscle Fatigue - A muscle’s inability to
contract after a period of prolonged exercise
Caused by:
• Lack of time to replenish fuel supply and/or
removal metabolic waste
• Lack of O2
getting to muscle
• Central command fatigue
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9. Background & Past Research
Hand-grip strength of young men, women
and highly trained female athletes (Leyk et al.
2006)
● 90% of females produced less force than
95% of males
● Female athletes significantly stronger
than untrained females
○ only as strong as 25% of untrained
male subjects
Gender differences and laterality in maximal
handgrip strength and controlled force
exertion in young adults (Kubota & Demura
2011)
● Males had greater grip strength than
females in maximal handgrip strength
due to sex difference in muscle mass
Grip and Pinch Strength: Normative
Data for Adults (Mathiowetz et al.
1985)
● Men stronger than women on
all hand strength tests
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10. Hypothesis
High intensity, short duration exercise will cause:
● a decrease in subject’s hand grip strength
○ more significant in female subjects
Decreased handgrip strength will increase EMG
activity
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11. Methods
● 16 subjects
○ 8 men & 8 women
○ 21-27 years old
● Pre-experiment questionnaire
○ Age
○ Gender
○ Level of fitness: Fit or Unfit
■ Fit=exercise 2x week
● Electromyography BIOPAC system
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12. Subject Set Up
EMG SS2L
electrode set
● forearm &
wrist of
dominant
arm
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13. Methods
● Negative Control: Baseline EMG at rest
● Control: EMG and PSI of Maximum and
Sub-maximum grip of dominant arm
● 15 bicep curls with 10 pound dumbbell
weight with dominant arm
● EMG & PSI of max and submax of
dominant arm taken:
○ immediately after exercise
○ 5 minutes after exercise
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14. Data Analysis - EMG
EMG was recorded by taking the average of each clench
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15. Results - Figure 1
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16. Results - Figure 2
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17. Results - Figure 3
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18. Results - Figure 4
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19. Results - Figure 5
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20. Summary of Results
● Both male and female
subjects exhibited increased
muscle activity 5 minutes
after exercise
● Muscle activity significantly
greater after exercise than
before
● Male subjects exhibited
greater values of maximum
handgrip strength than
female subjects 20

21. Discussion
● “Grip strength can indicate overall muscle tone”. (Stein, 2011)
○ Our results indicate, on average, women have a lower
handgrip strength than men.
○ This research implies that women have less muscle tone than
men.
○ What is muscle tone? Involuntary contractions of muscles
that are at rest.
○ This concludes that these involuntary contractions are more
common in men than in women.
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22. Discussion
Figure 1 shows fatigue after exercise
● EMG increased from baseline in both male and female
● women’s EMG values increased much larger than the men
○ more motor units were used → decreased arm strength
after exercise
No correlation between fit and unfit subjects: fit subjects
showed similar trends to that of the unfit (not shown in
graphs)
Our data was unreliable; data varied for each subject
● Very little change in EMG between male and female
subjects
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23. Summary
Hypothesis was neither confirmed or
refuted
● Results indicated increase in EMG activity
● Hand grip strength varied for individuals
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24. Sources of Error
● Bicep curls executed differently in subjects
● 15 reps insufficient for conclusive results
● Duration of squeeze
● Poor performance
or negligence from
subjects
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25. ● Equal ratio of fit to unfit subjects
● Subjects perform full extension bicep
curls until fatigued
● Use a hand gripper instead of dumbbell to
target desired muscles
● Squeeze dynamometer for
certain amount of time
● Place electrodes on biceps
● Account for body size
Future Directions
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26. Acknowledgments
Our fellow classmates and subjects for
their participation and food contribution.
Vanessa Miller-Sims for her mentorship,
guidance and support this semester.
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27. Questions or Comments
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