The following is an interview I did for Dr. GJohn Mullen from – https://www.trainingcor.com/blog/
What are the main muscles your study found activated during the kettlebell swing?
We looked at EMG within the medial hamstrings (semimembranosus and semitendinosus) and biceps femoris during three different kettlebell swing styles. The medial hamstrings were most active within all swing types. The hip hinge swing had the greatest hamstring activity, the double knee bend style had the lowest EMG, however it had the highest ratio of medial to lateral activation.
During what phases of the swing are these muscles more active?
The kettlebell swing involves an eccentric and concentric muscle action and has a stretch shortening cycle. The concentric phase of the movement has been found to have greater myoelectrical activity. The concentric phase is preceded by a rapid eccentric phase, which helps produce more force within the concentric phase. The increased force within this phase isn’t just due to the increased muscle activation, but is also due to storage and recovery of elastic energy. Additionally, increased time for the cross bridge to be attached, whilst the sarcomeres stay in a near optimal length (due to energy transfer into the elastic component). Of course the stretch reflex may be useful within exercises like the swing.
A common area of debate of the swing is the amount of forward flexion one should have, what do you think is appropriate?
Being based in Australia and avoiding most internet forums I’m not sure what people say on each side of the debate, however in my experience the answer is almost always it depends… Within our study we looked at three different swings: the hip hinge swing, squat swing and double knee bend swing. Of course there are inter-individual differences within the kinematics. Peak hip flexion may (or may not) be similar within each swing style, however, hamstring activity/length and torso angle may be different. The squat swing will require the shortest hamstring length even if there is similar degree of hip flexion because the hamstring is shortened across the knee. This will also keep the torso more upright, thus the squat swing may not offer the posterior chain as much of a challenge compared to the hip hinge swing style. For this reason many coaches may prefer the hip hinge style swing to the squat swing. If you wished to use a swing that offered a greater challenge to the anterior chain or a lesser challenge to the posterior chain the squat swing might be useful, however there may be other exercises better suited to training the anterior chain i.e. barbell squats. Lastly, the double knee bend swing is most commonly used within kettlebell sport and some people use it when performing the American swing (overhead swing). The double knee bend uses the forwards swing phase to reposition the kettlebell before the power leg action takes place. This may improve efficiency for the snatch or the overhead swing, obviously this an advantage within each sport, however the transfer may or may not be as specific to other sporting tasks.
What progressions for learning the KB swing do you feel work best?
There are different types of swings, which will require slightly different methods of teaching. The hip hinge swing may be the most applicable to many sports. One of the best methods I’ve found to teaching this style of swing is to reinforce top and bottom of a hip hinge. I commonly progress from a kettlebell deadlift to a RDL with a pause at the bottom and top. I look for neutral spine throughout the movement in both deadlift variations. I like to progress to the swing of the exercise once someone is competent with the RDL at a faster tempo (with no pause at the bottom). Also, for people that learn by ‘feel’, I’ve found proprioceptive taping to be helpful.
For the KB snatch, how does a KB alter the activity compared to using a barbell?
The kettlebell snatch and barbell snatch are both used within different sports. Within weightlifting you have three single attempts to correctly lift maximum weight. In contrast, the kettlebell snatch is commonly performed for 10 minutes with the goals of performing as many correct repetitions as possible. I think this contrast sums up the difference quite well from a strength and conditioning stand point. Of course you don’t need to perform 100+ reps with the kettlebell snatch, however, it isn’t well suited to single maximum effort like the barbell snatch. The kettlebell hooks onto the forearm and isn’t easily dropped, further, the kettlebell snatch has a downward phase and is easily swung back between the legs giving it more of a cyclical nature. So briefly, the barbell may be better suited to strength qualities, whilst kettlebells may be better suited to endurance.
What tips do you have for those with wrist pain while a KB snatch?
There can be a number of different causes of wrist pain during the snatch. Commonly, beginners perform the hand insertion phase poorly causing an impact upon the back of the forearm and rapid wrist extension. To avoid impact the hand insertion phase of the kettlebell snatch should take place before the arm is vertical. It has been recommended that it take place at ’11 o’clock’, to allow for a smooth transition to the lockout or fixation phase. Better lifters have low end-point variability, so beginners should work on ‘owning’ the lockout or fixation position, which will help to make each repetition as repeatable as possible. The wrist should be neutral or slight extended (if you can tolerate this) with the handle sitting diagonally across the palm within the fixation phase. If you are not involved in kettlebell sport I generally just say neutral. Lastly, building up your volume slowly is an important thing to do with any new movement.
What are some progressions for those working up to the KB snatch?
Like with most things there are many different ways that have merit. Commonly in kettlebell sport you would progress through the following exercises: swings, cleans, press, push press, jerk, half snatch. However, I’ve seen people that favour a hard style approach use the following exercises: swings, cleans, high pull, press, TGU, half snatch. Obviously, the swing is a very important variation as it is the bottom half of the snatch. Beginners commonly perform the hand insertion phase in the snatch poorly. The kettlebell should move into contact with the forearm slightly before the arm is vertical, many coaches often suggest 11 o’clock as mentioned above. If the hand is inserted or the kettlebell first contacts the forearm when it is vertical it will have a much greater impact. This is where the clean comes in, the clean helps the lifter learn the hand insertion phase below shoulder height and build control in a safer manner than going straight to the snatch. The TGU, press, push press and jerk should help the lifter build consistency at their end point (fixations or lockout) and of course if you don’t have the range of motion to perform a press correctly you shouldn’t be snatching. The benefit of the push press and jerk is that it teaches you to increase the speed that you need to lockout the kettlebell. In my opinion, consistently hitting the same end point will improve your efficiency and safety. Once you get to practicing the half snatch you may wish to break the snatch down into its upwards and downwards phases. When you are practicing the upwards phase you may wish to do a low, medium and height then perform the snatch, lower the kettlebell down to shoulder and release it like a clean. To practice the downwards phase simply clean and press the kettlebell overhead and then perform the downwards phase of the snatch. Once the lifter is confident with both phases they can combine them into the snatch.
What are some common beliefs of KB that still need to be researched?
Kettlebells have shown much promise as a training tool. There are a number of different areas that we need to research. As a follow up to this research it would be interesting to see how kettlebell training could fit into a rehab program, it would be particularly interesting to see an intervention within ACL rehab.