In his new P90 DVD set, the supertrainer Tony Horton drops the "X" for an all-levels-welcome version of his wildly popular 90-day program. The 10 workouts—including total-body and core on the floor routines—are mapped out for you in a follow-along schedule. The modification options to the mix of cardio and resistance moves "make every set possible" for a gymlike intensity, testers said, all in 25 minutes. "It doesn't get much better than that," one reviewer raved.

Circuit Training. Some gyms are set up to move people from machine to machine or exercise to exercise with little rest. This keeps the heart pumping and the muscles working. Work at each station for 30 to 45 seconds, or a certain number of reps, and keep the rest periods short, just the time it takes to walk from station to station. Like with supersets, this method combines the benefits of strength training and a bit of cardio at the same time Similarity in adaptations to high-resistance circuit vs. traditional strength training in resistance-trained men. Alcaraz, P.E., Perez-Gomez, J., Chavarrias, M., et al. Biomechanics Laboratory, Department of Physical Activity and Sport Sciences, San Antonio Catholic University of Murcia, Murcia, Spain. Journal of Strength and Conditioning Research; 2011 Sep;25(9):2519-27. Physical performance and cardiovascular responses to an acute bout of heavy resistance circuit training versus traditional strength training. Alcaraz, P.E., Sanchez-Lorente, J., Blazevich, A.J. Kinesiology and Biomechanics Laboratory, Department of Physical Activity and Sport Sciences, Universidad Católica San Antonio de Murcia, Guadalupe, Murcia, Spain. Journal of Strength and Conditioning Research; 2008 May;22(3):667-71.. It's easy to do a simple circuit at home, too: Lunges from wall to wall, sit ups in front of the TV, incline push ups on the coffee table, lateral hops over the sleeping puppy — work hard, move quick, get fit!
The EMG signals were filtered with a Butterworth band pass filter (cutoff frequencies 20 and 400 Hz). Then, the root mean square (RMS) of the EMG signal was automatically calculated with the software. During the incremental test, the EMG RMS was averaged for the last 5 EMG bursts of each step (at the end of each minute) and at exhaustion. During the time to exhaustion tests, the EMG RMS was averaged for the last 5 EMG bursts prior each time point measurement (10, 20, 30, 40, 50, 60, 70, 80, 90 and 100% of the time to exhaustion). EMG RMS of each muscle during the time to exhaustion tests was normalized by the maximal EMG RMS of the respective muscle obtained during the pre-exercise KE MVC performed at 100 deg/s. During the KE MVCs, maximal EMG RMS was averaged over a range of 20 deg extension (± 10 deg) around the peak torque.
3.  Move v-e-r-y s-l-o-w-l-y but smoothly. "Explosive" movement is not only nonproductive, but also dangerous. Plus, moving slowly eliminates momentum, which ensures constant muscle loading. Make a movement last about ten seconds. (A chin-up should take about ten seconds from the lowest to the highest point, and then another ten seconds from the highest to the lowest point. Same goes for a push-up.) There is nothing to be gained from fast movements. Moving slowly prevents injury. (There are over 30 million exercise related injuries annually in this country; most of these can no doubt be attributed to high-force movement.) Keep your movements low-force and high-intensity. An analogy: If you attempt to lift your car quickly, you will likely injure yourself even if using proper form. If you try lifting it slowly and intensely, your chances of injury are nil. Think of how you drive your car over speed bumps... fast will cause damage to the car's suspension, slow will not.

Children who participate in physical exercise experience greater loss of body fat and increased cardiovascular fitness.[23] Studies have shown that academic stress in youth increases the risk of cardiovascular disease in later years; however, these risks can be greatly decreased with regular physical exercise.[24] There is a dose-response relation between the amount of exercise performed from approximately 700–2000 kcal of energy expenditure per week and all-cause mortality and cardiovascular disease mortality in middle-aged and elderly populations. The greatest potential for reduced mortality is in the sedentary who become moderately active. Studies have shown that since heart disease is the leading cause of death in women, regular exercise in aging women leads to healthier cardiovascular profiles. Most beneficial effects of physical activity on cardiovascular disease mortality can be attained through moderate-intensity activity (40–60% of maximal oxygen uptake, depending on age). Persons who modify their behavior after myocardial infarction to include regular exercise have improved rates of survival. Persons who remain sedentary have the highest risk for all-cause and cardiovascular disease mortality.[25] According to the American Heart Association, exercise reduces the risk of cardiovascular diseases, including heart attack and stroke.[22]
Just shy of an hour long, this video is a killer aerobic kickboxing workout. You’ll throw punches and kicks in supercharged sequences as you follow along with the ebullient Billy Blanks. Don’t be surprised if you start talking back to the screen, especially when Blanks looks straight into the camera and declares, “I see you at home! Keep going!” Talk about motivation.
It is well known that exercise in the older population may prevent several diseases [1–4]. Reduced physical activity impairs the quality of life in elderly people with Alzheimer's Disease [4], Parkinson's Disease [5], and Depressive Disorders [6]. Moreover, musculoskeletal, cardiopulmonary, and cerebrovascular decline are associated with poor physical fitness because of the cumulative effects of illness, multiple drug intake, fatigue, and bed rest [7, 8]. The effects of physical activity and exercise programs on fitness and health-related quality of life (HRQOL) in elderly adults have been widely studied by several authors [9–11]. De Vries et al. [11] conducted a meta-analysis focusing on elderly patients with mobility problems and/or multimorbidity. Eighteen articles describing a wide variety of actions were analyzed. Most used a multicomponent training program focusing on the combination of strength, balance, and endurance training. In 9 of the 18 studies included, interventions were supervised by a physical therapist. Intensity of the intervention was not reported and the duration of the intervention varied from 5 weeks to 18 months. This meta-analysis concluded that, considering quality of life, the exercise versus no-exercise studies found no significant effects. High-intensity exercise appears to be somewhat more effective in improving physical functioning than low-intensity exercise. These positive effects are of great value in the patient population but the most effective type of intervention remains unclear. Brovold et al. [7] recently examined the effects of high-intensity training versus home-based exercise programs using the Norwegian Ullevaal Model [12] on a group of over-65-year-olds after discharge from hospital. These authors based their study on the Swedish Friskis-Svettis model [13] which was designed by Johan Holmsater for patients with coronaropathy to promote their return to work and everyday activities and improve their prognoses. This model includes three intervals of high intensity and two intervals of moderate intensity, each one lasting for 5 to 10 minutes. Included in each is coordination. Exercises consist of simple aerobic dance movements and involve the use of both upper and lower extremities to challenge postural control [13]. Exercise intensity was adjusted using the Borg Rating of Perceived Exertion (RPE) Scale. Moderate intensity was set between 11 and 13, and high intensity was set between 15 and 17 on the Borg Scale.