Unless you’ve been living under a rock for many years, or secretly invented a drug that provides the benefits of exercise without actually exercising, we all know we have to exercise. The real question when it comes to exercise is “how?”.
When most people think of cardio, they think of exercises that primarily use the legs: walking, running, and cycling. Even many otherwise fit people often neglect to do endurance work on their arms if their favorite cardio exercise is a leg exercise.
A cardio workout that includes both the arms and legs may be more beneficial than a workout that exercises either alone – Aerobic exercise training programs for the upper body. In fact, arm cardio all by itself has some interesting benefits: Med Sci Sports Exerc. 1988 Apr;20(2):136-41 – “Effect of arm training on central and peripheral circulatory function.”
The data suggest that endurance arm training as prescribed in this study elicits significant circulorespiratory function adaptations to support improved performance in both arm and leg work. Further, the findings suggest both a specific and general training effect, with the more dominant effect specific to arm work
This is pretty remarkable. So doing arm cardio can benefit the entire body, including the legs, not just the arms.
This raises an important question, and this is especially important for jogglers – Are the arms and legs in competition for cardiac output? Luckily, some scientists at the The Copenhagen Muscle Research Center, have already tried to answer this:
Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles.
(Emphasis is mine)
Leg blood flow 10% less during arm/leg exercise, than leg exercise alone? This is significant, and I must admit that when I joggle it certainly feels like this sometimes. But then at the same time, don’t forget the general fitness benefit from arm cardio suggested by the first study. So it may be 10% less than a higher blood output rate than if I were only running. In other words, a higher fitness level that is the result of leg/arm combination cardio is being compromised than a lower fitness level that is the result of mostly leg cardio. And don’t forget that unless you’re joggling with 3 heavy balls(or 4 or more light balls), juggling isn’t as intense as rowing, so it may be a lot less than 10%.
So if for whatever reason you can’t run or walk long distances, juggling by itself can also provide aerobic benefits. Also, if you joggle, or you are considering joggling, your leg speed may be slightly compromised, but it’s not really a big deal and the juggling may be making you fitter than if you were just a runner.