Procedures
A within-participants crossover design was used to compare 6-RM and EMG activity in the competition style bench press (flat bench - wide grip) with: 1) narrow and medium grip width and 2) on a +25º inclined and −25º declined bench with a wide grip which was defined as the maximum grip width permitted in the bench press competition rules (81 cm spacing between palms). Narrow grip width was set at participants’ biacromial distance (42.0 ± 3.5 cm) and medium grip width as 50% (wide - narrow grip; 61.5 ± 3.5 cm). Five sets of 6-RM presses were performed in randomized order. Before the experimental test, all participants performed two familiarization sessions in which individualized 6-RM loads were identified for all five bench press conditions (familiarization 1: wide, medium and narrow grip; familiarization 2: wide grip on an inclined and declined bench). Between three and six sets with 5 minutes rest between each attempt were used to find the individualized loads, with 6-RM chosen as the typical training load recommended to gain strength in the training period in which the study was conducted (Ratemess et al., 2009). A minimum of six days separated the two familiarization sessions and the experimental test. Under experimental testing, all five sets of 6-RM were performed in one session.
Performance enhancing clothing and body strapping (e.g. bench shirt, elbow wraps) were not permitted during testing, but the participants were allowed to use lifting belts, wrist wraps and chalk to improve barbell grip. A 20 kg Olympic barbell (Leoko, Er Equipment, Denmark), an adjustable bench (Pivot 430 flexi bench, Sportsmaster, Norway) and a power rack (Pivot 480, Sportsmaster, Norway) were used for testing.
Before the familiarization sessions and experimental test, a standardized warm-up protocol typically used by the powerlifters was conducted. All warm-up sets were performed with the athletes’ preferred grip width on a flat bench. The warm-up sets consisted of 20 repetitions with a barbell only (optional), 10 repetitions at 50%, four repetitions at 70%, two repetitions at 80% and one repetition at 90% of the 6-RM load. A three minute rest separated each warm-up set (Saeterbakken et al., 2011) with a five minute interval between each bench press variation.
The 6-RM lifts were not performed according to competition rules, which stipulate a deliberate stop phase in which the barbell rests on the chest, however, participants were instructed that the barbell had to touch the chest gently without any bouncing, before being lifted up to full elbow extension. Each repetition was performed at a self-selected speed and with no pauses between repetitions. Participants were instructed to maintain the head, shoulder blades and buttocks in contact with the bench in all variations. Two test leaders acted as spotters and assisted participants in the preload phases. Loads were decreased or increased if participants either failed to perform six repetitions, or indicated they could lift more.
Bench Press in Pakistan
Recordings
To identify the start and end of each repetition, a linear encoder was synchronized with the EMG recording system (Musclelab 4020e, Ergotest Technology A/S, Langesund, Norway). The linear encoder (at a sampling frequency of 100 Hz) identified the vertical displacement (Figure 1a) in addition to the beginning, end and duration of each 6RM attempt. A goniometer (ss21 L, Biopac System Inc., USA) was attached to the fulcrum of the elbow, in line with the humerus and ulna (Figure 1b). The accuracy of the goniometer was ±2º measured over 90º, with repeatability of < ±1º.
An external file that holds a picture, illustration, etc.
Object name is hukin-57-061-g001.jpg
Figure 1a-b
The vertical displacement of the barbell (1a) and the elbow position (1b) performing the different bench press conditions.
Before attempting the 6-RM lifts in the experimental test, participants’ skin was shaved, abraded and washed with alcohol before placement of the self-adhesive electrode. Bipolar sliver-silver chloride electrodes (11 mm contact diameter, 20 mm center-to-center distance) were placed over the center of the muscle belly along in the principal direction of muscle fibers of the pectoralis major (PM) (clavicular and sternocostal part), triceps brachii (TP), biceps brachii (BB), anterior deltoid (AD), posterior deltoid (PD) and latissimus dorsi (LD), using anatomical landmarks and according to the recommendations of SENIAM and similar studies (Hermens et al., 2000). The signal was amplified and filtered using a preamplifier located as near to the pickup point as possible. The preamplifier had a common mode rejection rate of 100 dB. The raw EMG signals were band pass filtered (fourth-order Butterworth filter) with cut-off frequencies of 8–600 Hz. The filtered EMG signals were root-mean square (RMS) converted using a hardware circuit network (frequency response 0–600 kHz, with an average constant of 100 ms, total error ± 0.5%). The RMS-converted signal was re-sampled at the rate of 100 Hz using a 16 bit analog-to-digital converter (AD637). The mean RMS value of all six repetitions in each condition was used for further analyses. Commercial software (Musclelab v8.13) was used to analyse the position data from the linear encoder, the elbow angle from the goniometer and the EMG data.
