Rodríguez-Rosell, D, Yáñez-García, JM, Torres-Torrelo, J, Mora-Custodio, R, Marques, MC, and González-Badillo, JJ. Effort index as a novel variable for monitoring the level of effort during resistance exercises. J Strength Cond Res 32(8): 2139-2153, 2018-This study aimed to analyze the acute mechanical and metabolic response to resistance exercise protocols (REPs) defined by 2 variables: the first repetition's mean velocity and the percentage of velocity loss (%VL) over the set. The product of these 2 variables was termed the effort index (EI) and was used as an indicator of the degree of fatigue induced during each REP. Twenty-one resistance-trained men (11 in full squat [SQ] and 10 in bench press [BP]) performed 16 REPs separated by 72 hours. Relative loads used (50, 60, 70, and 80% 1-repetition maximum) were determined from the load-velocity relationship for the SQ and BP, whereas volume was objectively determined using the %VL attained over the set (10, 20, 30, and 45% for SQ, and 15, 25, 40, and 55% for BP). Lactate concentration and velocity against the load that elicited a ∼1.00 m·s (V1 m·s load) were measured before and after each REP. Post-exercise velocity with the V1 m·s load and lactate concentration were significantly different (P < 0.01-0.001) from pre-exercise after all REPs. A very close relationship was found between the proposed EI and %VL with the V1 m·s load (r = 0.92-0.98) and post-exercise lactate concentration (r = 0.91-0.95) in both exercises. The correlations between this new index and fatigue indicators such as VL allow us to gain further insight into the actual degree of effort incurred during resistance exercise. In addition to being a valuable addition for training monitoring, the proposed EI could also be used as an independent variable in training studies by equalizing the effort between different interventions.

This study aimed to compare the effect of 6 weeks of resistance training or combined resistance training and change of direction exercises on physical performance and motor skills in futsal players. Thirty-four futsal players were divided into full squat group (SG, n = 12), combined full squat and change of direction exercises group (S+CDG, n = 12) and control group (CG, n = 10). The resistance training for SG consisted of full squat with low load (~45-58% 1RM) and low volume (4-6 repetitions), whereas the S+CDG performed the same resistance training program combined with loaded change of direction. Sprint time in 10 and 20 m, change of direction test, countermovement vertical jump (CMJ) height, maximal strength and force-velocity relationship in full squat exercise, kicking speed ball (BS) and repeated sprint ability (RSA) were selected as testing variables. Both experimental groups showed significant improvements for CMJ, BS and all strength parameters. Only SG resulted in significant sprint gains, whereas S+CDG also achieved significant improvements in RSA. The CG remained unchanged after training period. No significant differences were found between both experimental groups. These findings suggest that only 12 sessions of either lightweight resistance training alone, lifting the load at maximal intended velocity or combined with change of direction exercises is enough to improve several physical and skills capacities critical to futsal performance in adult players.

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Key points• This study deals with the cellular mechanisms involved in firing rate modulation in vivo in the oculomotor system where there are requirements for high firing rates by motoneurons.• The study demonstrates that glutamate effects depend on the recruitment threshold and, presumably, motoneuron size.• Mid-and high-threshold motoneurons in response to glutamate decrease their voltage threshold and strengthened the tonic and phasic components of the firing rate.• In a functional context, motoneurons could be recruited at lower recruitment threshold and could generate a strong muscle contraction under glutamate modulation to perform saccadic eye movements with different velocities and/or to maintain the eye in different eccentric positions in the orbit.• Our results suggest that the recruitment and firing behaviour of ocular motoneurons can be modified in vivo by glutamatergic synaptic inputs. It provides a link between cellular function and behavioural motoneuron output.Abstract Studies in alert preparations have demonstrated that ocular motoneurons exhibit a phasic-tonic firing rate related to eye velocity and position, respectively. The slopes of these relationships are higher in motoneurons with higher recruitment threshold and have been proposed to depend upon synaptic input. To investigate this hypothesis, motoneurons of the rat oculomotor nucleus were recorded in a brain slice preparation in control conditions and during glutamate (5 μM) application to the bath. Glutamate did not affect membrane potential or input resistance, but produced a decrease in rheobase and depolarization voltage as a function of the current needed for generating a maintained repetitive discharge (recruitment threshold current). In addition, glutamate compressed the range of recruitment threshold current (0.1-0.4 nA) as compared to the control (0.15-0.7 nA). Glutamate exposed motoneurons showed an increase in the tonic frequency gain and the peak frequency. Such increments depended on the recruitment threshold current and the last recruited motoneurons almost doubled the tonic frequency gain (35.2 vs. 57.9 spikes s −1 nA −1 ) and the peak frequency (52.4 vs. 102.6 spikes s −1 ). Finally, glutamate increased the spike frequency adaptation due to a significant increase in the phasic firing component as compared to the tonic one. In conclusion, glutamate modulates tonic and phasic discharge properties as a function of the recruitment threshold current and, presumably, motoneuron size. These findings contribute to understand the link between cellular functions and motoneuron discharge during oculomotor behaviour.