An Athlete Is Holding a 5kg Dumbbell in Their Hand

Short Answer

An athlete is holding a 5kg dumbbell in their hand maintaining an elbow joint angle of approximately 100° of elbow flexion. Rearrange the equation "∑CWM + ∑ACWM = 0" to solve for the muscle force (F₁) needed to maintain static equilibrium, when:
F₂ x d₂ = clockwise moment (negative) (∑CWM)
F₁ x d₁ = anti-clockwise moment (positive) (∑ACWM)
Weight force of arm, hand and dumbbell mass x acceleration due to gravity (F₂) = 9kg x 9.81m/s²
Perpendicular distance from joint axis to muscle force (d₁) = 0.04m
Perpendicular distance from joint axis to weight force (d₂) = 0.36m