Resistance training (i.e., weightlifting) is increasing in popularity and is now recognized as an important component of a general exercise program. The current Physical Activity Guidelines for Americans recommend regular muscle-strengthening exercise for healthy men and women, older adults and adults with chronic conditions. The proposed benefits of regular resistance training typically focus on improved neuromuscular function, strength, endurance and bone density. However, a growing body of evidence suggests resistance exercise may also cause positive adaptations to the cardiovascular system.
Most cardiovascular events such as heart attack and stroke are caused by a blood clot (i.e., thrombosis) that partially or completely blocks blood flow, thus restricting delivery of oxygen to important organs and tissues. This is a considerable problem in the U.S. as approximately 2.7 million Americans experience a clot-induced event each year. Acute bouts of exertion are known to transiently increase blood clotting activity, potentially leading to exercise-induced complications.
Regular exercise training, however, causes adaptations that reduce the potential to create a blood clot and increase the capacity to dissolve a clot once it forms. This is one of the ways that regular exercise is theorized to improve heart health. A substantial body of knowledge indicates that aerobic exercise in particular, causes these beneficial adaptations. Much less is known, however, about the effects of resistance training on blood-clotting potential.
In a recent study, 16 healthy women and men completed a resistance training program that was based on American College of Sports Medicine (ACSM) guidelines for improving muscular strength. Participants trained three times per week for eight weeks. Each training session included two to three sets of eight exercises, targeting all major muscle groups, performed at an intensity that corresponded with 60%-80% of 1 rep max. The key finding of this study was a significant training-induced reduction in plasminogen activator inhibitor-1 (PAI-1), a protein that inhibits activity of the plasminogen system, which dissolves blood clots. The reduction of this inhibitory protein suggests that the capacity to dissolve blood clots is enhanced after resistance training.
PAI-1 concentration is independently associated with adverse events such as stroke and myocardial infarction. These findings suggest that eight weeks of resistance training reduces the risk of thrombotic (blood clotting)events in healthy adults. The mechanisms as to how this occurs are unclear. The plasminogen system also plays a role in skeletal muscle remodeling, so the reduction in PAI-1 observed in this study also suggests a mechanism for training-induced muscle hypertrophy.
The Bottom Line?
Not only is resistance training an important component of an exercise program because of its effects on muscular fitness and bone density; it may also induce adaptations that reduce risk of cardiovascular complications. The study reviewed here had a small sample and more research is needed but it still may have important implications for balancing one’s exercise regimen.
Balancing the regimen
There are three basic elements to a balanced training regimen: aerobic exercise, strength training and flexibility. We’ve talked about the benefits of aerobic exercise and its effect on cardiovascular health. A perfect example is brisk walking as it pushes oxygen through to your heart and lungs, causing them to work more efficiently. It can help to lower blood pressure, regulate blood sugar, regulate weight, strengthens the immune system and lastly, helps reduce falls in older patients.
We’ve learned that strength training not only keeps your musculo-skeletal system strong, we now know that it may have positive effects on the cardiovascular system as well. The last component, and most avoided, is stretching. Muscular flexibility helps maintain your range of motion, helps muscle recovery and may help reduce your chance of injury.
There are several disciplines out there that incorporate combinations of these exercise types for more efficiency. It’s a matter of what “floats your boat”. Swimming(resistance and cardio), Yoga (flexibility and balance), Pilates, Barre and Lagree (strength, posture and flexibility). Always consult your doctor before starting a new exercise program and then go for it.