This scoping review presents an overview of physical fitness parameters in rhythmic gymnastics as well as the association of fitness with gymnasts’ performance, competitive level, and age. PubMed, Scopus, and Sport Discus databases were searched. Of the 586 records retrieved, 41 studies met the inclusion criteria (n = 1915 participants). The included studies examined flexibility, aerobic capacity, muscle power, muscle endurance, muscle strength, sprint speed, agility, balance, and coordination. Performance was associated with flexibility, aerobic capacity, lower-limb muscle power, agility, muscular endurance, balance, and coordination from a young age. Flexibility, aerobic capacity, and muscle power were, in general, higher in high-level gymnasts than in low-level gymnasts or controls. Older rhythmic gymnasts demonstrated higher scores than the younger ones in flexibility, aerobic capacity, balance, and sport-specific coordination but not in muscle endurance, while some studies reported a decline in muscle power with age. Supplementary physical fitness training improved all physical abilities irrespective of the gymnasts’ level. Rhythmic gymnastics training alone improved muscle power, agility, speed, muscular endurance, and balance to a lesser extent than targeted fitness training. Muscular strength, speed, and agility are largely under-researched in rhythmic gymnastics. Emphasis should be given to targeted strength and power training due to the high mechanical loads placed on skeletally immature athletes.

Τhis study examined changes in hip joint flexion angle after an intermittent or a continuous static stretching protocol of equal total duration. Twenty-seven female subjects aged 19.9 ± 3.0 years (14 artistic and rhythmic gymnasts and 13 team sports athletes), performed 3 min of intermittent (6 × 30 s with 30 s rest) or continuous static stretching (3 min) of the hip extensors, with an intensity of 80–90 on a 100-point visual analogue scale. The order of stretching was randomized and counterbalanced, and each subject performed both conditions. Hip flexion angle was measured with the straight leg raise test for both legs after warm-up and immediately after stretching. Both stretching types equally increased hip flexion angle by ~6% (continuous: 140.9° ± 20.4° to 148.6° ± 18.8°, p = 0.047; intermittent: 141.8° ± 20.3° to 150.0° ± 18.8°, p = 0.029) in artistic and rhythmic gymnasts. In contrast, in team sports athletes, only intermittent stretching increased hip flexion angle by 13% (from 91.0° ± 7.2° to 102.4° ± 14.5°, p = 0.001), while continuous stretching did not affect hip angle (from 92.4° ± 6.9° vs. 93.1° ± 9.2°, p = 0.99). The different effect of intermittent vs. continuous stretching on hip flexion between gymnasts and team sports athletes suggests that responses to static stretching are dependent on stretching mode and participants training experience.

Gastrocnemius medialis (GM) architecture and ankle angle were compared between flexibility trained (n = 10) and not trained (n = 6) female athletes, aged 8–10 years. Ankle angle, fascicle length, pennation angle and muscle thickness were measured at the mid-belly and the distal part of GM, at rest and at the end of one min of static stretching. Flexibility trained (FT) and not trained athletes (FNT) had similar fascicle length at the medial (4.19 ± 0.37 vs. 4.24 ± 0.54 cm, respectively, p = 0.841) and the distal part of GM (4.25 ± 0.35 vs. 4.18 ± 0.65 cm, respectively, p = 0.780), similar pennation angles, and muscle thickness (p > 0.216), and larger ankle angle at rest (120.9 ± 4.2 vs. 110.9 ± 5.8°, respectively, p = 0.001). During stretching, FT displayed greater fascicle elongation compared to FNT at the medial (+1.67 ± 0.37 vs. +1.28 ± 0.22 cm, respectively, p = 0.048) and the distal part (+1.84 ± 0.67 vs. +0.97 ± 0.97 cm, respectively, p = 0.013), larger change in joint angle and muscle tendon junction displacement (MTJ) (p < 0.001). Muscle thickness was similar in both groups (p > 0.053). Ankle dorsiflexion angle significantly correlated with fascicle elongation at the distal part of GM (r = −0.638, p < 0.01) and MTJ displacement (r = −0.610, p < 0.05). Collectively, FT had greater fascicle elongation at the medial and distal part of GM and greater MTJ displacement during stretching than FNT of similar age.

The association between force–time characteristics of isometric leg press (ILP) and countermovement jump (CMJ) with vastus lateralis (VL) muscle architecture, was examined in 19 female athletes (aged 23.2 ± 5.4 years). Peak force (PF), average rate of force development (ARFD) and rate of force development (RFD) at different time epochs were calculated from the force–time curve, as well as CMJ jump height and power. Significant correlations were found between ILP-PF and CMJ power (r = 0.658, p < 0.01), while both variables were correlated with VL thickness and fascicle length (r = 0.471 to 0.648, p < 0.05). Significant correlations were also observed between ILP-RFD epochs and VL fascicle length (r = 0.565 to 0.646, p < 0.05) and between CMJ height with VL thickness (r = 0.523, p < 0.05). Furthermore, positive correlations were found between ILP and CMJ in ARFD (r = 0.625, p < 0.01) and RFD epochs (r = 0.464 to 0.566, p < 0.05). ILP-PF and muscle thickness accounted for 52.8% (p = 0.002) of the variance in CMJ power. These results suggest that isometric force time characteristics are associated with power generation during dynamic muscle actions. Furthermore, VL muscle thickness and fascicle length are associated with rapid force production in female athletes, irrespective of the type of muscle action.

This cross-sectional study examined gastrocnemius medialis fascicle length (FL) and anatomical cross-sectional area (ACSA) in female volleyball athletes aged 8–18 years, in an attempt to investigate morphological growth changes during childhood and adolescence. Methods: Eighty-nine athletes were assigned to five groups: 8–10, 10–12, 12–14, 14–16 and 16–18 years old. Height, body mass, leg and calf length were measured, and maturity offset was calculated from anthropometrics. FL and ACSA were assessed using ultrasonography. Results: FL was longer and ACSA was larger in the 12–14 y group compared with the 8–10 y group (4.31 ± 0.60 vs. 3.66 ± 0.40 cm, p = 0.008 and 13.08 ± 3.01 cm² vs. 9.98 ± 2.07 cm², p = 0.018, respectively). However, there were no differences in FL or ACSA among the groups aged between 12 and 18 years (p > 0.573 and p > 0.352). Notably the percentage increase in ACSA between the youngest (8–10 y) and the oldest group (16–18 y) was twofold greater than the percentage increase in FL (49% vs. 24%). Significant correlations were found between anthropometric characteristics FL and ACSA (r = 0.366–760, p < 0.001). Conclusions: These data indicate that there is a rapid increase in FL and ACSA from the age of 8 y until the age of 14 y, which is a crucial time frame for muscle growth.

Background/Objectives: This cross-sectional study examined gastrocnemius medialis (GM) and vastus lateralis (VL) muscle architecture in pre-, circa- and post-peak height velocity (PHV) female volleyball athletes. Methods: Muscle architecture (fascicle length: FL; pennation angle: PA; muscle thickness: TH) was assessed in 144 athletes using ultrasonography. Stature, body mass, femur and calf length were measured. Maturity index was calculated from anthropometrics. Athletes were classified as pre-PHV, circa-PHV and post-PHV. Results: Fascicle length of the GM and VL was longer in post-PHV compared to pre-PHV athletes (d = 1.50 and d = 2.22, respectively, p < 0.001). Differences between circa and post-PHV athletes were observed only in GM (d = 0.84, p = 0.005). TH showed progressively greater values in both muscles across maturity stages (p < 0.001). PA was larger in post- compared to pre-PHV athletes, only in GM (p = 0.009). When all athletes were examined as one group, correlations were found between anthropometrics, maturity index and muscle architecture (r = 0.164–0.744 and 0.284–0.622, respectively, p < 0.05). In addition, in the GM, body mass and training experience accounted for 40% of the variance in FL (p < 0.001), whereas body mass and FL explained 66% of the variance in TH (p < 0.001). In the VL, stature and body mass explained 49% of the variance in FL (p < 0.001), while body mass, fascicle length, and maturity index explained 68% of the variance in TH, with maturity exhibiting a negative coefficient (p < 0.001). Conclusions: FL and TH of both muscles demonstrated larger values between pre- and post-PHV. GM and VL exhibited different morphological patterns, probably due to bone development and loading. Athletes’ body mass best predicted FL in both muscles, whereas the greater values in TH in post- compared to pre-PHV athletes appear to be associated with body mass and FL. The influence of maturity on VL thickness diminishes at more advanced stages of development.