Table 2.

Muscle Strength

Study	N	Age range/mean	Diagnoses	Non-SCD Control	Relevant Outcome Measures	Findings Related to Physical Impairments and Function
Brownell et al. 202037	22	9–19 years/13.8 ± 3.3 years	HbSS	No	Maximum left and right handgrip force Knee extension and flexion maximal torque Jump height Jump peak power	Right handgrip (23.2 ± 10.3 kg) Left handgrip (22.5 ± 11.0 kg) Knee extension (55.2 ± 30.8 ft/lb). Knee flexion (22.4 ± 13.9 ft/lb) Jump height (33.2 ± 9.9 cm) Jump peak power (1705 ± 894 W)
Dougherty et al. 201140	35	5–13 years/9 ± 2.2 years	HbSS	Yes	Handgrip force Vertical squat jump peak power	Participants with SCD had significantly lower dominant hand maximal handgrip force and jump peak power than the controls Dominant handgrip force (SCD: 12.7 ± 3.3; controls: 15.2 ± 5.1 kg); p < 0.008 Jump peak power (SCD: 882 ± 298; controls: 1167 ± 384 W); p < 0.001
Dougherty et al. 201838	21	5–17 years/11 ± 4 years	HbSS	Yes	Maximal handgrip force Ankle plantarflexion maximal torque Vertical squat jump peak power	Significantly lower handgrip force, ankle plantarflexion torque at two angles, and jump peak power in participants with SCD compared to controls Maximum handgrip strength lower in participants with SCD (p<0.01) Ankle plantarflexion torque at two angles lower in participants with SCD (p<0.05) Jump peak power lower in participants with SCD (p<0.04)
Dougherty et al. 202039	21	5–20 years/11 ± 4 years	HbSS	Yes	Maximal handgrip force Plantarflexion and dorsifleixion maximal torque Knee extension torque Jump height Vertical squat jump peak power	Significantly lower handgrip force, ankle plantarflexion torque at 10° and 20°, and jump peak power in participants with SCD compared to controls Dominant handgrip force (SCD: 15.6 ± 8.6 kg; controls: 27.6 ± 9.6 kg); p < 0.05 Ankle plantarflexion torque: −10° (SCD: 44.7 ± 22.2 Nm; controls: 53.6 ± 36.9 Nm); NS 0° (SCD: 39.0 ± 20.0 Nm; controls: 50.0 ± 31.0 Nm); NS 10° (SCD: 27.3 ± 17.1 Nm; controls: 42.2 ± 24.7 Nm), p < 0.05 20° (SCD: 21.2 ± 11.8 Nm; controls: 33.5 ± 19.5 Nm); p < 0.05 Ankle dorsiflexion torque; NS: −10° (SCD: 9.8 ± 5.7 Nm; controls: 12.5 ± 6.9 Nm) 0° (SCD: 12.3 ± 7.3Nm; controls: 15.7 ± 10.7 Nm) 10° (SCD: 13.3 ± 8.3 Nm; controls: 16.9 ± 12.1Nm) 20° (SCD: 14.9 ± 9.3 Nm; controls: 18.1 ± 13.4 Nm) Knee extension peak torque (SCD: 49.6 ± 27.6 Nm; controls: 65.8 ± 44.1 Nm); NS Knee flexion torque (SCD: 22.4 ± 13.3 Nm; controls: 23.3 ± 17.7 Nm); NS Jump height (SCD: 25.2 ± 5.2 cm; controls: 28.0 ± 8.3 cm); NS Jump peak power (SCD: 1054.3 ± 477.8 W; controls: 1487.6 ± 811.1 W); NS
Jacob et al. 201241	31	10–17 yers	HbSS, HbSC	No	e-Diary created for the study	14.3% of participants with SCD reported general weakness
Moheeb et al. 200710	50	9–12 years/10.1 ± 0.076* years	HbSS	Yes	Handgrip force Back and leg muscle force Vertical jump height	Participants with SCD had significantly lower handgrip strength, leg and back muscle force, and vertical jump height compared to controls Right handgrip force (SCD: 13.1 ± 0.5* kg; controls: 17.0 ± 0.9* kg); p < 0.001 Left handgrip force (SCD: 12.6 ± 0.5* kg; controls: 14.9 ± 0.7* kg); p < 0.001 Leg muscle force (SCD: 23.3 ± 0.7* kg; controls: 28.1 ± 1.4* kg); p < 0.001 Back muscle strength (SCD: 23.3 ± 0.7* kg; controls: 30.9 ± 1.4* kg); p < 0.001 Jump height (SCD: 17.7 ± 0.8* cm; controls: 23.1 ± 0.8* cm); p < 0.001
Patra et al. 201342	330	9 months-14 years/7.60 (males) 9.22 (females)	SCA	Yes	Symptom list	Generalized weakness reported in 87.7% (SCA) vs. 60% (controls)
Wali & Moheeb 201135	93	10.4–14.6 years/12.81 ± 0.136* years	SCA	Yes	Handgrip strength Leg and back muscle strength	Participants with SCD on hydroxyurea had significantly lower right handgrip and leg muscle strength compared to controls Right handgripa (SCD: 16.02 ± 0.254*; controls: 18.23 ± 0.192*); p < 0.05 Left handgripa (SCD: 15.42 ± 0.231*; controls: 16.02 ± 0.255*); NS Leg strengtha (SCD: 29.45 ± 0.544*; controls: 33.24 ± 0.437*); p < 0.05 Back strengtha (SCD: 30.2 ± 1.2*; controls: 32.6 ± 1.3*); NS

Abbreviations: N = number of participants with sickle cell disease; NS = not significant; SCA = Sickle Cell Anemia; SCD = Sickle Cell Disease. Results are reported as mean ± standard deviation, except where noted otherwise.

^*Standard error.

^aUnknown units of measure.