So I'm sure many of you have seen them. It looks like a normal treadmill, but with a bubble around it and costs upwards of $75,000 (for the top-end model). The Alter-G is becoming a topic of conversation in the distance running world and for good reason. The high impact nature of long distance running can put athletes at risk for overuse injuries. With the Alter-G you can train at lower percentages of your body weight thus taking some stress off your legs. Initially it seemed this device would be best suited for injury recovery and allow athletes to begin "running" sooner during rehabilitation. Obviously the detraining effects associated with not-running during injury can be detrimental to athletes. Allowing runners to return to running (albeit at a lower body weight) sooner could augment some of these detraining effects. More recently coaches have begun experimenting with using the Alter-G to "supplement mileage". The thinking here being, "If runner X can run 100 miles per week normally without risking injury he may be able to run upwards of 120 miles per week if we do some of that mileage at a lower % body weight on the Alter-G". You can see the potential here...More Aerobic Training!
Supplementing running with other modes of aerobic cross training has become popular for long distance runners with the same reasoning as using the Alter-G. Bigger Aerobic Base = Greater Running Potential. When comparing swimming, cycling, eliptical(ing?) and pool running I think the consensus would be that pool running offers the best benefit for runners since the movement patterns are the most similar to the sport in which the athlete's training to compete. There has been some research done in recent years examining pool running that have yielded some intriguing findings. When in water we're dealing with resistance throughout the entire movement which results in different motor recruitment patterns when compared to on-land running. Also, in order to mimic muscle activity to on-land running the perceived effort in the pool must be considerably higher (i.e. they have to work harder for the same benefit). I had often wondered about this same concept on the Alter-G. Are the motor patterns/muscle activity the same as on-land running? What makes running at a lower % body weight feel so much easier?
Just last month in the Journal of Sport Sciences researchers from UNLV's Department of Kinesiology and Nutrition Sciences published the first peer-reviewed paper to my knowledge examining this topic. Here's the abstract and if you're at a University I'm sure you can track down the full text version as well. They compared muscle activity with EMG while running at 100%, 115% and 125% of preferred running speed on the Alter-G at 100%, 90%, 80%, 70% and 60% body weight. The findings...Running at a lower % body weight resulted in less muscle activity (makes sense!). However the decrease in % body weight did not result in an equal decrease in muscle activity (the two followed a similar, but not equal descending trend). I think these finding are promising and may provide empirical support for coaches thoughts on supplementing mileage with the Alter-G. It seems that muscle activity patterns are diminished when running at a lower % body weight, but the % contribution from different muscles is similar to on-land running. This is one of the knocks on pool running...Since you're dealing with resistance throughout the entire movement different muscles are asked to do more/less of the total work. This data suggests that running on the Alter-G doesn't create an issue with over/under use of certain muscles and replicates on-land running more closely than pool running.
With only 1 published study we can't jump to conclusions just yet. These findings are very intriguing and this topic necessitates further investigation for sure. I'm still curious about what's really happening with the % body weight issue. For instance if someone runs 80 miles per week on a treadmill at 100% body weight and then runs another week of 80 miles at say 80% body weight. Are we burning more/less calories? What about total work completed? In races we're carrying 100% body weight, so does this have a deleterious effect on subsequent performances? Obviously there's still some questions to answer here, BUT if you have an extra $75,000 laying around the Alter-G seems to be a good tool for both injury recovery AND as a cross-training modality...
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