Caffeinated chewing gum enhances maximal strength and muscular endurance during bench press and back squat exercises in resistancetrained men

Li Ding ¹ Jue Liu ² Yi Yao ¹ Li Guo ³ Bin Chen ⁴ YinHang Cao ^1* Olivier Girard ⁵

• ¹ School of Athletic Performance, Shanghai University of Sport, Shanghai, China
• ² Huashan Hospital, Fudan University, Shanghai, Shanghai Municipality, China
• ³ School of Exercise and Health, Shanghai University of Sport, Shanghai, China
• ⁴ Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, China
• ⁵ School of Human Sciences, University of Western Australia, Perth, Western Australia, Australia

Caffeinated chewing gum, known for its rapid absorption, has not been previously studied for its effects on maximal strength and muscular endurance in resistance exercise. The aim of this study was to determine the efficacy of caffeinated chewing gum on maximal strength and muscular endurance during bench press and back squat exercises. In a randomized, double-blind design, 16 resistancetrained males (age: 21.6 ± 2.0 years, height: 176.8 ± 6.1 cm, mass: 79.6 ± 8.8 kg) chewed either caffeinated gum (3 mg/kg) or a placebo gum on two occasions, one week apart. After a standardized warm-up, participants chewed the gum for 5 min before performing maximal strength test (onerepetition maximum [1RM]) and muscular endurance test (60% 1RM repetitions to failure) for bench press and back squat exercises. 1RM, number of repetitions, ratings of perceived exertion and pain perception were assessed. Caffeinated chewing gum significantly improved 1RM in both bench press (105.3 ± 14.5 vs. 100.3 ± 13.4 kg, +5.0% [95% confidence interval (CI): 3.7 -6.3%], p < 0.01) and back squat (172.3 ± 20.2 vs. 161.9 ± 22.3 kg, +6.8% [95%CI: 4.1 -9.5%], p < 0.01) exercises with small effect size (Cohen's d: 0.36 [95%CI: 0.09 -0.63] and 0.49 [95%CI: 0.22 -0.76], respectively), despite similar levels of pain perception and RPE (p > 0.05). It also increased the number of repetitions in both bench press (20 ± 5 vs. 17 ± 4, +18.8% [95%CI: 11.5 -26.1%], p < 0.01) and back squat (37 ± 11 vs. 28 ± 8, +33.3% [95%CI: 23.1 -43.4%], p < 0.01) exercises with moderate-to-large effect size (Cohen's d: 0.76 [95%CI: 0.48 -1.03] and 0.89 [95%CI: 0.60 -1.16], respectively), despite similar levels of pain perception and RPE (p > 0.05). Caffeinated chewing gum (3 mg/kg) improved both maximal strength and muscular endurance during bench press and back squat exercises in resistancetrained men. This approach offers a practical and time-efficient method to improve training performance while minimizing the risk of side effects.