Page 59 - Journal of Special Operations Medicine - Winter 2016

Table 1 Subject Pretest Characteristics in a prescribed target HR training zone (60% to 85%
Traditional HR max ), and calisthenics including 3 × 1 minute of push-
KB KB + Run AF PT ups and 3 × 1 minute of sit-ups, with 30 seconds rest in
Characteristic (n = 7) (n = 6) (n = 7) between sets, followed by a 5-minute cool-down. Table
Male:Female 5:2 2:4 3:4 2 lists the exercise session breakdown for each group.
Age, years 30.4 (6.9) 35.8 (4.8) 34.0 (2.9) Maximum HR was calculated for the KB + run and the
traditional PT groups using the following ACSM for-
Height, cm 174.0 (11.7) 167.9 (7.3) 166.5 (8.0) mula: MHR = 206.9 − (age in years × 0.67).
Weight, kg 81.4 (12.4) 79.5 (14.9) 81.8 (16.2)
Body fat, % 23.2 (8.3) 26.0 (8.3) 25.9 (7.3) Table 2 Exercise Session Breakdown
Data are given as mean (standard deviation). AF, US Air Force; KB, KB + High-
kettlebell; PT, physical training. KB only Intensity Run Traditional PT
Dynamic warm- Dynamic warm- Dynamic warm-
peak and average HR values as calculated by the HR up (10 min) up (10 min) up (10 min)
monitor after all training sessions.
KB swings Run at 60% to
(10 min) 85% HR
Experimental Procedures KB swings Run > 85% HR (20 min) max
Subjects participated in 10 weeks of supervised PT and (10 min) (10 min) max 3 × 1-min push-ups
were pretested and posttested to determine the effects 3 × 1-min sit-ups
of each exercise intervention. Both preintervention and Cool down Cool down (5 min) Cool down
postintervention data collection consisted of 2 separate (5 min) (5 min)
days of testing with 48 hours of recovery between test- HR max , maximum heart rate; KB, kettlebell; min, minute; PT, physical
ing sessions. The first testing session included height, training.
weight, body fat percentage, maximal grip strength,
pro agility, vertical jump, and 40-yard dash. The second Before the study, investigators received training and
testing session followed USAF physical fitness testing instructional DVDs on continuous one-arm KB swing
guidelines in AFI 36-2905 to include waist circumfer- technique from World Kettlebell Club founder and
ence, 1-minute maximal push-ups, 1-minute maximal trainer, Valery Federenko (Figure 1A–1D). Subjects in
sit-ups, and 1.5-mile run. Before each testing session, the KB and KB + run groups were instructed to follow
subjects received instructions and demonstrations on all the one-arm swing technique, switching arms every five
physical tests. repetitions. The first 2 weeks of training consisted of
instructional sessions and progressed in duration of KB
The 1.5-mile run was assessed on an indoor track, fol- swings from 4 × 1 minute with 1 minute of rest between
lowing AFI 36-2905. Vo 2max was estimated based on sub- sets to 5 × 2 minutes with 30 seconds’ rest between sets
jects’ 1.5-mile run times. The following ACSM equation by the end of week 2. The duration of KB training re-
was used to estimate maximal aerobic capacity: Vo 2max mained at 5 × 2 minutes for weeks 3–10.
(mL/kg/min) = 3.5 + 483/(time in minutes).
KB weights were selected based on proper technique ex-
After baseline testing, participants were sequentially ecution and were progressively increased based on par-
assigned to one of three training groups using a block ticipants’ technique and perceived effort throughout the
design based on the primary outcome variable (i.e., 1.5- study. Male subjects in the KB group and the KB + run
mile run time) to ensure an even distribution of pretest group began the study using 8kg to 12kg KBs and fin-
run times per group. Participants in the KB group com- ished the study using 12kg to 18kg KBs. Female subjects
pleted a dynamic warm-up for 10 minutes, followed by began the study using 6kg to 8kg KBs and progressed to
10 minutes of KB swings (five sets of 2 minutes with 30 10kg to 14kg KBs the final week of the study.
seconds’ rest between) and a 5-minute cool-down con-
sisting of light cycling, jogging, or walking. Participants Statistical Analyses
in the KB + run group completed a dynamic warm-up for A repeated measures design was used to detect differ-
10 minutes, then 10 minutes of KB swings, immediately ences between pretraining and posttraining scores.
followed by 10 minutes of continuous high-intensity Analysis of variance (F test) was used to compare the
running (>85% of age-predicted HR max ) and a 5-minute variability between the groups. Post hoc analysis using F
cooldown. Participants assigned to the traditional USAF tests was performed when significant interactions were
training group trained in accordance with AFI 36-2905. observed. The statistical analyses were performed using
Subjects engaged in 20–30 minutes of running and cal- the Statistical Package for Social Sciences version 20.0
isthenics (i.e., push-ups, sit-ups). This included a dy- (IBM Corp., https://www.ibm.com) with an α level set
namic warm-up for 10 minutes, 20 minutes of running at p ≤ .05.

Physiological Effects of Kettlebell Swing Training 43