The interference effect attenuates strength and hypertrophic responses when strength and endurance training are conducted concurrently; however, the influence of training frequency upon these responses remain unclear when varying ratios of concurrent strength and endurance training are performed. Therefore the purpose of the study was to examine the strength, limb girth and neuromuscular adaptations to varying ratios of concurrent strength and endurance training. Twenty four men with >2 years resistance training experience completed 6 weeks of 3 d·wk-1 of i) strength training (ST), ii) concurrent strength and endurance training ratio 3:1 (CT3), iii) concurrent strength and endurance training ratio 1:1 (CT1) or iv) no training (CON) in an isolated limb model. Assessments of maximal voluntary contraction via isokinetic dynamometry leg extensions (MVC), limb girth and neuromuscular responses via electromyography (EMG) were conducted at baseline, mid-intervention and post-intervention. Following training, ST and CT3 conditions elicited greater MVC increases than CT1 and CON conditions (P 0.05). In conclusion greater frequencies of endurance training performed increased the magnitude of the interference response on strength and limb girth responses following 6 weeks of 3-d·-1 of training. Therefore, the frequency of endurance training should remain low if the primary focus of the training intervention is strength and hypertrophy.