Background/Objectives: Resistance training (RT) is a key strategy to counteract age-related declines in muscle strength and physical function. β-hydroxy-β-methylbutyrate (HMB) has been proposed as a complementary supplement to enhance these adaptations. However, the additional effects of RT plus HMB (RT+HMB) compared with RT alone remain unclear. This systematic review and meta-analysis evaluated the effects of RT+HMB versus RT alone on body composition, muscle quality (MQ), and physical function in older adults. Methods: Following PRISMA guidelines (PROSPERO: CRD420251144810), six databases (PubMed, Scopus, Cochrane Library, CINAHL, Web of Science, and ScienceDirect) were searched up to July 2025. Randomized controlled trials comparing RT+HMB with RT alone were included. Methodological quality was assessed with the PEDro scale and risk of bias using Cochrane RoB 2. Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Results: Ten trials (n = 596) met inclusion criteria. RT+HMB produced modest and borderline significant improvements in handgrip strength (SMD 0.24; 95% CI 0.00–0.48; p = 0.05) and moderate benefits in Short Physical Performance Battery (SPPB) scores (SMD 0.54; 95% CI 0.12–0.95; p = 0.01). No significant effects were observed for gait speed, appendicular lean mass, MQ, fat mass, or body weight (p > 0.05). Five trials (50%) were rated at high risk of bias, limiting confidence in pooled estimates. Conclusions: HMB supplementation combined with RT may yield modest improvements in functional performance, particularly handgrip strength and overall physical function, without statically significant effects in body composition and MQ. Further high-quality RCTs are warranted to confirm its clinical relevance.

Background: Craniocervical pain and temporomandibular disorders (TMDs) are prevalent, interconnected conditions. While Movement Representation Techniques (MRTs) are cognitive interventions targeting central pain mechanisms, their specific efficacy here lacks synthesis. This study systematically analyzes the effectiveness of MRTs, such as motor imagery (MI) and action observation (AO), on pain and function in individuals with craniocervical and orofacial pain. Methods: A systematic review of RCTs (PROSPERO: CRD420251155428) was conducted following PRISMA guidelines. Four databases were searched for studies applying MRTs (MI, AO, laterality discrimination) to adults with craniocervical or orofacial pain. Primary outcomes were pain and functionality. Methodological quality was assessed using the PEDro scale and Cochrane RoB 2 tool. Results: Eight RCTs (n = 362) were included. Methodological quality was high (PEDro scores 8–9). MRTs significantly increased Pressure Pain Threshold (PPT) in the masseter, trapezius, and cervical regions. Functional improvements included enhanced cervical range of motion and sensorimotor control. AO consistently demonstrated superior outcomes. However, results for orofacial variables were derived from asymptomatic subjects. Results for cervical muscle strength were inconsistent. Conclusions: MRTs, especially AO, show potential to reduce pain and improve function in craniocervical disorders. Evidence in symptomatic orofacial pain populations is non-existent. Protocol heterogeneity and limited research groups necessitate further high-quality, multicenter RCTs to establish robust clinical guidelines.