It helps your heart
If you think the aerobic system has nothing to do with resistance training, you are mistaken. For starters, it fuels recovery, not just between repetitions and sets of exercises, but after the session itself. It also instigates heart-healthy changes in the cardiovascular system, such as allowing more blood to get to the muscle and enabling waste products to be cleared more efficiently. Of course, the heart itself is a muscle, and strength training has been shown to increase the size of the chamber responsible for pumping blood around the body. This allows more blood to be delivered to the exercising muscles with every beat.
It lowers the risk of diabetes
Diabetes is one of the fastest growing diseases in the west. Traditionally, aerobic exercise has been recommended to improve glucose metabolism, but in a recent study four months of strength training was found to increase glucose uptake by an average of 23% , indicating that it might be equally as effective. Strength training also seems to improve glucose metabolism both in subjects with normal glucose metabolism and in those who already have an abnormal response.
It reduces blood pressure
Strength training used to be thought to increase blood pressure but, increasingly, evidence shows it can reduce blood pressure acutely (as the result of a single session) and chronically (in the long term). This is good news, because hypertension is commonly associated with heart disease, stroke and kidney problems. Improved strength also reduces stress on the heart. In one 12-week study, subjects worked out with weights to strengthen lower body muscles - by the end of the study period, their blood pressure rose significantly less in the course of lifting activities.
It bulks up bones and keeps joints healthy
Building bone density is the first line of defence against osteoporosis, which affects one in three women over the age of 50. Research shows that bone mineral density (BMD) is closely related to the strength of the muscles attached to those bones. In a study, twice-weekly resistance training over a year resulted in a 6.3% increase in BMD of the lumbar spine. The women taking part were postmenopausal - a time when BMD is usually plummeting. The control group (who did no strength training) lost 3.7% of their BMD over the same period.
While weight-bearing activities such as running and high-impact aerobics are great for BMD, they influence only the particular parts of the skeleton that are loaded by the activity. As well as preserving BMD, strength training reduces the risk of osteoporotic fractures by improving balance and muscle strength, thereby decreasing the risk of falls.
Meanwhile, movement keeps the joint structures bathed in sticky synovial fluid, and weight-training also strengthens the connective tissues - that is, ligaments, tendons and cartilage. These factors can alleviate symptoms of osteoarthritis.
It may improve your cholesterol profile
First, a cholesterol recap: HDL good, LDL bad. High levels of low-density lipoprotein (LDL) and total cholesterol are associated with a higher risk of coronary heart disease, while high-density lipoprotein (HDL) cholesterol is beneficial to heart health, helping to prevent the development of athersclerosis. There's been conflicting evidence regarding whether strength training can help to improve cholesterol profile, but it seems that postmenopause (when heart-protective oestrogen is out of the picture) resistance training can be very beneficial. In research from the University of Oklahoma, postmenopausal women who took part in 12 weeks of training using resistance bands experienced a significant rise (13%) in HDL cholesterol levels despite not losing weight or body fat - the poorer the initial cholesterol profile, the greater the subject's improvement.
It keeps you regular
A study that involved 13 weeks of strength training, including exercises for the abdominals, found a 56% acceleration in gastrointestinal tract time (GITT). A long GITT is associated with colon cancer, not to mention digestive problems.
It's the way to an easier life
If you think strength training is all about aesthetics, think again. Put it this way: if you can lift a 10kg weight, that 5kg bag of shopping isn't going to pose a challenge. Being stronger helps you get through daily tasks with less effort and more energy. Anyone who has had children has experienced the effects of "progressive overload" strength training: first when the baby was growing inside you and then after his or her birth, when you continued to nurse, pick up and carry your little bundle of joy despite his or her rapidly advancing weight.
· Weights For Weight Loss, by Sam Murphy, is published next week by Kyle Cathie at £14.99. To order a copy for £13.99 (inc UK p&p), call 0870 836 0875 (theguardian.com/bookshop).
