This research overview looks at a paper in this month’s Journal of Strength and Conditioning Research that sparked my interest from the title. I found myself wondering what the premise of the research was and why it was chosen by the researchers. The idea was for Inacio et al to gain a greater understanding of the effects of changes in bodyfat on certain performance characteristics and this was achieved by adding an external upper body load in the form of a weighted vest. Another aim of the research was to look at any gender differences in simulated fat mass increase and performance decrement.

It was hypothesized that there would be a significant drop in vertical jump, 40 yard sprint, 20 yard sprint and 20 yard shuttle test performances (it is interesting to see the effect that the NFL combine testing is having on research, or is it the other way round?) when an external load of 2% body weight was added, a significant and progressive drop in performance would be seen when loads of 2, 4, 6, 8 and 10% body weight was added and that female participants would show greater decreases than men in all loading conditions. The reasoning for the final hypothesis was that as a result of greater percentage bodyfat amongst women and effectively increasing that through external loading would lead to a greater fat mass to lean mass ratio than compared to men who would start with a lower bodyfat percentage.

There were 46 participants (21 men and 25 women) in the study that made up one experimental group, all were considered untrained, normally active and none participated in an organised sport or physical activity. Each participant completed vertical jump, 40 yard sprint (20 yard sprint measured at the same time) and 20 yard shuttle tests in random order at 0, 2, 4, 6, 8 and 10% external loads that were achieved with weighted vests. Testing took place over 4 sessions interspersed by at least 48 hours for each participant with the first session being body composition testing (DEXA) and baseline (0%) measures. Subsequent sessions were each focused on one physical test and loading order was randomised to minimise the impact of fatigue.

Given the nature of the study with gender, the 6 test conditions and the 4 tests compared, the results took some interpreting. Significant drops were seen in vertical jump scores with the only gender difference being between a significant drop between the 8-10% scores females that wasn’t seen amongst the males. Women also had a significantly greater drop compared to men for every loading condition compared to baseline except at the 6% condition. A similar trend was seen during the twenty yard shuttle test with women showing a greater performance decrement than men in all but the 4% condition.

During the 20 yard sprint a significant drop was seen between 2-6% in women but not men and between 6-8% in men but not women, a progressive drop was seen through all 5 conditions in both genders. In the 40 yard test, performance decrements began at 2% for both men and women but women were significantly more affected by the external load and as a result experienced greater drops in performance at 4,6,8 and 10%.

The results demonstrate the negative effects that higher fat mass can have on performance in anaerobic events. Putting this in a little bit of perspective helps, a 2% increase in mass for a 70kg person is 1.4kg. It would be interesting in future studies, as mentioned by the authors, to look at more athletic populations to if similar performance decrements exist.

Inacio, M., Dipietro, L., Visek, A.J. & Miller, T.A. (2011) Influence of upper body external loading on anaerobic exercise performance. Journal of Strength and Conditioning Research 25(4) pp. 896-902/

This overview covers research by McBride et al (2010) comparing the squat and box squat. The authors made a tentative hypothesis that by removing the stretch shortening cycle from the movement, by using a box squat, they would find negative effects on kinetic variables and muscle activity.

8 competitive powerlifters with at least 3 years squatting experience (Height: 179.61 ± 13.43 cm; Body Mass: 107.65 ± 29.79 kg; Age: 24.77 ± 3.22 years; and 1 repetition maximum (RM): 200.11 ± 58.91 kg) were used as participants in the study.

Participants visited the laboratory on 2 occasions separated by at least a week. On the first occasion they underwent 1RM squat testing. 1RM squat was obtained using a standard 1RM procedure achieving a knee angle of 70° measured with a goniometer. On the second occasion participants performed 1 repetition at 60%, 70% and 80% each for the squat and the box squat in a randomised order. The box squat involved an eccentric phase of movement to sitting on a box for 1 second followed by a concentric phase and the squat was performed with a quick transition between both phases. Peak force and power were measured during the concentric phase as was muscle activity of the vastus lateralis, vastus medialis, biceps femoris and longissimus.

Peak force was found to be significantly higher during the box squat in the 70% of 1RM trials and peak power was significantly higher during the box squat in the 80% of 1RM trials. Muscle activity of the biceps femoris was significantly greater during the squat at 60% of 1RM trials and the vastus lateralis was significantly more active during the squat in the 70% of 1RM trials.

The authors conclude by stating that there is little difference between the kinetic variables and muscle activity involved during the squat and box squat. They state that the box squat may be a useful tool for training athletes that have a concentric only component to their sport but that a stretch shortening cycle is a vital component in most sports and as such a squat that utilises a stretch shortening cycle may be of greater benefit.

McBride, J.M., Skinner, J.W., Schafer, P.C., Haines, T.L. & Kirby, T.J. (2010). Comparison of kinetic variable and muscle activity during a squat vs a box squat. Journal of Strength and Conditioning Research 24:12 pp. 3195-3199.

This review focuses on golf and a paper by Sell et al (2007) that looked at the physical characteristics of golfers across a number of bands of proficiency. The authors hypothesised that those golfers with lower handicaps would score higher in the recorded measures of strength, flexibility and balance.

The study looked at 257 male, right handed golfers (age: 45 ± 12.8 years, height: 180.6 ± 6.5 cm, weight: 87.9 ± 12.6 kg) participated in the study and they were grouped according to their handicap (<0, 1-9, 10-20). Isometric strength was tested using isokinetic dynamometry on shoulder internal and external shoulder rotations and hip adduction and abduction.

Range of motion and flexibility was measured at the shoulder, hip, hamstring and torso using a goniometer. It measured internal/external rotation, flexion/extension and abduction of the shoulder, flexion/extension and adduction/abduction of the hip, supine hamstring flexibility using the knee extension test and, with pelvis stabilised, maximum torso rotation.

Postural stability or balance was measured using a Kistler force plate under eyes closed and eyes open conditions. Participants were barefoot and  tested on each leg individually, they were asked to focus on a target 2 metres in front at eye level and maintain their balance while data was collected in medial/lateral and anterior/posterior planes for 10 seconds and the same procedure for eyes closed was repeated with the obvious difference.

Results showed that the <0 handicap group had significantly greater right hip abduction, right hip adduction, left hip abduction, right torso rotation and left torso rotation strength than both of the other groups and significantly greater right shoulder internal rotation, right shoulder external rotation and left shoulder external rotation strength than the 10-20 handicap group. The 0-9 handicap group also had significantly greater right torso rotation and left torso rotation strength than the 10-20 handicap group. There were also significantly better scores for the <0 handicap group over the other groups and for the 0-9 group over the 10-20 handicap group for many of the balance and flexibility scores, for full details the orginal paper can be consulted.

The paper concludes by saying ample evidence is provided for the efficacy of training programs to be designed to improve golf performance because highly proficient golfers showed significantly greater multiple joint strength and flexibility as well as better balance.

For an individualised strength and conditioning program to improve your driving distance, driving consistency and putting distance control get in contact.

• Sell, T.C., Tsai, Y.S., Smoliga, J.M., Myers, J.B. & Lephart, S.M. (2007). Strength, flexibility and balance characteristics of highly proficient golfers.  Journal of Strength and Conditioning Research, 21(4) pp. 1166-1171.