Data collected included demographic information (age), anthropometric measures (height, body mass, BMI, and loaded BMI), fitness measures (Illinois agility test, 1 RM bench press, 1 RM back squat, 1 RM military shoulder press, 1 RM hexagonal bar deadlift, grip strength, loaded pull-ups, 7 stage sit-up, push-ups, progressive shuttle run test and 1.2 km run) and a specially designed task performance measure (OSPA). The outcome measures were those commonly employed within this population as a tool for entry onto selection courses and as a measure of performance [12
]. These tests were those chosen by the agency’s strength and condition coach and outside the control of the researchers.
Age, height, and body mass: Age (years) and height (cm) measurements were self-reported by selection course candidates. Self-reported height has been used previously in tactical populations and has been shown to be reliable [15
]. The weight of the candidate was measured on the barrier test day using standard procedures [15
] on a scale (Tanita BC82Fitplus, IL, USA).
BMI and LBMI: Body mass index (BMI) was calculated based on candidates’ self-reported height and weight measurements and using standardized procedures (BMI = weight (kg)/[height (m)]2
]. Loaded body mass index (LBMI), a new measure, was further calculated using the standardized BMI formula, with weight adjusted to combine the candidates usual body weight with the amount of load carried (LBMI = loaded weight (kg)/[height (m)]2
) for the loaded tasks.
Illinois agility test: The Illinois agility test was administered using a standardized approach as described in previous literature [17
]. The test was conducted on a flat, non-slip surface with eight cones arranged in a 9.14-by-9.14 metre square with four cones placed to mark the boarders of the square and another four cones aligned halfway through the agility course (4.57 m) so that the candidate could weave through the markers. When instructed, the candidate accelerated to the top corner cone, quickly turned and accelerated back towards the middle set of cones to weave up and back around the cones. Once weaving up and back through the four cones, the candidate accelerated to the furthest corner cone, again making a quick turn around and sprinting back to the finish. Candidates were familiar with the test and were allowed one attempt. Time was recorded and measured to the nearest 0.01 s using a handheld timer (Hart Sports, Zillmere, Australia).
1 RM strength protocol: Muscular strength is commonly documented as a measure of a repetition maximum (RM). A one repetition maximum (1 RM) load refers to the maximum amount of weight a person can lift in a single voluntary effort with proper technique [18
]. Although a 1 RM lift is recognized to be the most accurate method to determine strength, it can often be time consuming. Alternative methods are widely used and include deriving a 1 RM from multiple-repetition sets (e.g., 3 RM) [18
All candidates were familiar with 1 RM testing protocols having to record personal 1 RM data, derived from a 3RM lift, in a training diary and submit their results to the specialist unit’s head strength and conditioning coach as part of their pre-selection preparation. Each candidate converted their 3 RM to a 1 RM value for the (1 RM = weight × reps × 0.0333 + weight) bench press, back squat, military shoulder press and deadlift. As all candidates were required to track their results, they were familiar with this testing and protocol. Candidates completed the 1 RM testing in pairs in their own time under the supervision of the unit’s strength and conditioning coach using the Jim Wendler formula (1 RM = weight × reps × 0.0333 + weight) to convert their 3 RM to a 1 RM estimate. The final training cycle concluded two weeks prior to the OPSA testing. Standard protocols for these measures are described below [19
1 RM bench press: Candidates completed the bench press using a 20 kg Pendlay brand barbell (MDUSA, SC, USA), Garage gym brand bumper weight plates (LifeFitness, Rosemont, IL, USA) and Hammer Strength bench support (LifeFitness, Rosemont, IL, USA). Standard bench press protocol required candidates to lay flat on their back, feet flat on the ground, with scapulae and buttocks in contact with the bench. The barbell was grasped at slightly wider than shoulder width to allow for a 90 degree angle when the bar was at the lowest point. Candidates were required to lower the weight in a slow, controlled manner until the barbell just touched the chest then pushed back up to the starting position (1 repetition).
1 RM back squat: Candidates completed the back squat using a 20 kg Pendlay brand barbell, Garage gym brand bumper weight plates and Hammer Strength Power Rack. The back squat protocol required candidates to step under the barbell located in the supporting arms on the power rack. Again, the barbell was grasped at slightly wider than shoulder width or was altered based on mobility of the individual. The candidate was required to position the barbell on their upper back, just above the trapezius. Standard foot width required feet to be just wider than hip-width apart. When ready, the candidate removed the weighted barbell from the rack supports, took two steps back then performed the eccentric movement of the squat, flexing at both knees and hips. Appropriate depth of the squat was determined when the central line of the femur was parallel to the ground. When successful depth was achieved the candidate extended the hip and knee joints and returned to the starting position (1 repetition).
1 RM military shoulder press: Candidates completed a military shoulder press using a Pendlay brand barbell, Garage gym brand weight plates and Hammer Strength Power Rack. Standard shoulder press protocol required candidates to step under the barbell located in the supporting arms on the squat rack. The shoulder press was conducted using a pronated grip (back of hands facing towards candidate) with a grip width wider than shoulder width to allow for 90 degrees of flexion at the elbow. Candidates were required to place the barbell over the clavicles, take two steps back and position their feet to be hip-width apart with a slight bend in their knees. When ready, candidates lifted the bar overhead to fully extend the elbows then eccentrically lowered the bar back down to the chest (1 repetition).
1 RM hexagonal bar deadlift (HBD): Candidates completed a deadlift using an Australian Barbell Company hexagonal deadlift bar (weighing 24 kg) (Australian Barbell Company, Mordialloc, VIC, Australia) and Garage gym brand bumper weight plates on a rubber matted area. Standard deadlift protocol required candidates to stand inside the hexagonal bar with feet placed hip-width apart. When ready, the candidate would squat down to grasp the bar while keeping heel contact with the floor and the head in a neutral position. The lift started with arms fully extended and progressed to an upward lift of the bar while extending the knees and hips. Once standing the candidate placed the bar back on the ground in a smooth, controlled manner (1 repetition). Candidates completed the deadlift on their own and used the Jim Wendler formula to convert their 3 RM to a 1 RM estimate.
Grip strength: Grip strength of both dominant and non-dominant hands were measured using a handgrip dynamometer (Takei Scientific Instruments, Niigata City, Japan). The task was standardized by adjusting the dynamometer so that the base of handgrip rested on the first metacarpal and the handle was in contact with the middle aspect of the four fingers. The candidates were required to squeeze the dynamometer with maximal isometric effort. Candidates were permitted one attempt before the value was recorded to the nearest kilogram.
Loaded pull-ups: On the barrier test day, the loaded pull-up was performed using a 17 kg plate carrier vest. The pull-ups were conducted using an under-grasp grip (back of hands facing away from officer) with a grip width wider than shoulder width to allow for a 90 degree angle when upper arms were parallel to the ground. Candidates were instructed to flex their knees to 90 degrees with ankles crossed behind the body. The 17 kg weighted plate carrier vest was worn over the shoulders with weight distributed on front and back of the upper body. To complete a successful repetition, the candidate could not swing the legs during the pull-up movement and the chin was required to raise above the level of the bar. Pull-ups were repeated until fatigue and the maximum number successfully performed was recorded.
7 stage sit-up: The 7 stage sit-up test is used to measure the relative strength of the abdominal muscles and was administered using a standardized approach as per Dortkamp [20
]. In brief, the candidates were required to start in a sit-up position, lying on their back with hands by their sides and knees bent to 90 degrees. Each candidate was asked to perform a controlled movement, as outlined in the protocol, until reaching the final stage if able. With each sequential stage the requirements increase in difficulty, with the final stage requiring the candidate to perform a sit-up with a 5 kg weight behind their head. The final stage that was successfully completed was recorded as the candidate’s final score. Candidates were required to achieve a minimum score of 3 to be successful.
Timed push-ups: The push-up assessment for muscular endurance involved completing as many good-quality repetitions as able in 60 s. Candidates began in a prone position with arms fully extended, only hands and feet were in contact with the ground. Once instructed to begin, the candidates were asked to bend at the elbows and lower their body to the floor. Candidates lowered to the floor until their upper arms were parallel with the ground and then extended their elbows until returning to the starting position (1 repetition). To be considered successful, candidates were required to produce smooth and controlled movements. The final full repetition that was successfully completed was recorded as the candidate’s final score. Candidates were required to achieve a score greater than 40 to be successful.
The 20 m progressive shuttle run test (PSRT): The PSRT is a multi-stage fitness test used to measure the candidates maximal aerobic power, the test was administered following standard procedure as described by Robinson et al. [19
]. In brief, the test requires candidates to complete 20 m shuttle runs before the next successive beep (administered by audio compact disc from the Australian Sports Commission). Shuttle runs are performed continuously, with successive increases in speed after each level until voluntary exhaustion is reached. If the candidate achieves two consecutive failed attempts their score is recorded, and the candidate is withdrawn from the test. During the assessment, heart rates (HR) were monitored using the Team Polar HR system, to ensure near maximal/maximal efforts. Scores were recorded in Level and Stage (e.g., level 10, stage 6) and converted to the number of shuttles performed in total.
1.2 km Run: Candidates were required to complete a distance of 1.2 km (0.74 miles) on foot in shorts, t-shirts and shoes of their choosing. The distance was identified with markers and candidates were required to complete the distance as quickly as possible. Results were recorded in minutes and seconds using a handheld stopwatch. The use of stopwatches to record run times in these populations has been reported in the literature and is common practice due to the venue, size of testing group and ease [1
]. Furthermore, stopwatch use as a viable alternative to other forms of electronic timing for the accurate and reliable collection of group data is likewise acknowledged in the literature [21
Occupational-specific physical assessment (OSPA): On the first day of the selection course (two weeks after the above testing), candidates conducted the OPSA following a 15 min formal warm up. As per dedicated and pre-established protocols, the assessment was conducted on a dry, non-slip surface wearing standard specialist police attire and loads (‘black role’ mean load weight 28.43 ± 0.54 kg) as required by all candidates. Some variable external load between candidates did exist due to differences in body armour size and personal preferences. The candidates completed initial familiarization run throughs until comfortable with the requirements before a final testing run was completed.
Correct set up of the assessment required six marker cones, a 70 kg mannequin dummy with a 10 kg plate carrier vest secured over the mannequin upper body, handheld stopwatch and recording equipment. Candidates started at base line, facing towards a series of parallel lines identified with marking cones placed at distances of 10 m and 20 m (Figure 1
). Once on the base line, candidates were asked to stand with one foot on or behind the starting line with their muzzle raised and aimed at a target in front of them (up to 30 m away). On command, candidates were required to complete a series of timed sequential actions as follows: (1) sprint to the first opposing 10m parallel line; (2) upon arriving at the 10 m mark, candidates were to quickly drop into a prone position and crawl to the next opposing 20 m line; (3) on reaching the 20 m mark opposite the starting line, candidates were required to sling their primary weapon, and raise the upper body of an 80 kg dummy off the ground and quickly drag the dummy backwards until the 10 m line was reached; (4) on reaching the 10 m line, the dummy was to be lowered to the ground, candidates dropped to a kneeling unsupported position, raised the muzzle of their primary weapon and took aim at a target with accuracy confirmed by the assessor when the laser sighting system aligned and was held momentarily on the target (termed sight picture); (5) on achieving a sight picture, the candidate again slung their weapon and picked up the dummy and dragged it a further 10 m backwards, where, on arrival of the starting line, the dummy was lowered and a kneeling firing position was taken; (6) once achieving a sight picture on the target, the candidate stood up and sprinted to the 10 m mark where the same kneeling unsupported firing position was adopted and a sight picture taken; (7) this action was repeated to the 20 m line and was followed by a 180 degree turn (keeping lowered body posture) leading into the same kneeling firing position; (8) on achieving a sight picture on a second target (behind the starting line), the candidate stood up and sprinted back to the 10 m marker and, again, adopted the firing position and sight picture; (9) this was repeated once more, where, on reaching the starting line, the candidate slung their weapon, picked up and dragged the dummy as quickly as possible for the full length of the course (20 m) before again adopting the kneeling firing position (facing towards the starting line); (10) on achieving the sight picture, the candidate stood and sprinted as quickly as possible to the start line to finish the assessment.
If the candidate fell over, they were given up to three minutes recovery time before recommencing the assessment. The overall time to complete the OSPA was measured in minutes and seconds for each candidate. There were no required standards to pass the assessment, but all candidates were required to complete the course as fast as possible and were under the scrutiny of the barrier day testing staff.