This invention relates generally to exercise machines to enhance physical fitness, and more particularly to a machine which entails concurrent peddling and rowing actions. 
To remediate many of the physical fitness problems of the sedentary individual, various forms of exercisers have been contrived to develop muscular strength and endurance.  Most exercisers in current use fall either into the isometric or isotonic class.  An isometric exerciser functions to sustain a muscular contraction and therefore operates on static tension; whereas an isotonic exerciser, which is adapted to repeatedly raise or lower a weight or other load, brings into play dynamic tension. 
From the standpoint of overall physical fitness enhancement, neither isotonic nor isometric forms of exercise are adequate, for these exercises fail to contribute in an appreciable degree to improvements in circulatory-respiratory endurance, an important aspect of well-being. 
In recent years, a third training technique has been developed by experts in the physiology of exercise and physical therapy to improve overall physical fitness.  This new technique, which combines the best attributes of isotonic and isometric training, has been designated isokinetic training.  In isokinetic exercise, maximum dynamic tension is developed throughout a range of motion. 
When performing isotonic or isometric exercises, strength development is not achieved equally throughout the range of motion.  In isotonic exercise, the magnitude of isotonic resistance must be limited to the largest load that can be moved at the weakest point in some range of motion.  This resistance will therefore be less than maximum during the rest of the range and thus will not load the muscle to its full tension-developing capacity in much of its shortening range.  Moreover, in isotonic training, the exercise speed is subject to considerable acceleration and is therefore unstable and unpredictable. 
On the other hand, isometric exercise takes place against a load which prevents external movement and offers resistance inherently proportional to the muscle's static tension-developing capacity at one shortening length.  No dynamic work at all is carried out; hence the intrafiber power developed is inherently restricted. 
In my prior Spector U.S. Pat.  No.  4,148,479, issued Apr. 10, 1979, there is disclosed a push-pull isokinetic exerciser in the form of a hydraulic bar having telescoping inner and outer tubes provided at their ends with handle pieces.  A hydraulic bar of this type offers substantially uniform resistance to motion throughout its entire range of compression and expansion strokes and therefore demands an evenly applied muscular force to effect such motion in either direction of movement.  It calls for the effort and work of the isometric technique, while offering the weight resistance of the isotonic method, thereby combining the best aspects of both types of exercise. 
An exerciser of the type disclosed in the Spector patent may be held between the hands or between either foot and either hand and then expanded and contracted at virtually any body position, thereby making it possible to exercise almost all body regions and muscle groups.  The practical difficulty with an exerciser of this type is that one is able to exercise only one set of muscles at a time, and this may lead to uneven development; for the user tends to favor the hands over the feet. 
Stationary bicycle exercisers are known in which the user, sitting on a raised bicycle seat, operates pedals with his feet to turn a front wheel whose rotation is subject to an adjustable resistance to vary the required effort.  Such machines are suitable for developing the leg muscles, but afford little exercise to other parts of the body. 
Stationary rowing machines are known, such as that disclosed in the Lawton U.S. Pat.  No.  2,825,563, in which an individual sitting on a seat slideable on bed rails, graps the handles of pivotally-mounted oars coupled to air cylinders, thereby providing for the simultaneous exercising of back leg and arm muscles. 
Also known are exercisers which combine rowing and peddling actions.  Thus the "Home-Bike" exerciser manufactured by B. H. Beistegui is provided with swingable handlebars whose back and forth movement by an individual sitting on a bicycle seat is resisted by an adjustable friction pad.  A Home-Bike exerciser, in its rowing function, fails to offer substantially uniform resistance to motion throughout its entire range of swing and does not therefore afford the full advantages of isokinetic training. 
The following patents represent prior art generally relevant to the present invention:
U.S. Pat.  Nos.  3,266,801 (1966), 432,598 (1890), 1,015,071 (1912), and 1,916,714 (1933) deal with rowing exercise machines in which each one is coupled to a fluid cylinder. 
U.S. Pat.  Nos.  3,966,201 (1976), 2,783,044 (1957), 2,419,998 (1947) and 4,188,030 (1980) disclose various forms of cycle exercisers which include both foot pedals and handlebars. 
While rowing machines have made use of hydraulic cylinders coupled to the oars, the nature of these machines is such that the hydraulic cylinders coupled to the outstretched oars may be placed at right angles to the bed on which the rower's seat slides, as in U.S. Pat.  No.  1,015,071.  In the case of the cycle exercisers disclosed in the prior art, hydraulic cylinders have not been used in connection with the rowing elements, for in this context it is not possible to place the cylinders in the manner heretofore used with rowing machines.  In the present invention, a hydraulic cylinder is so placed as to be straddled by the seated individual so as not to interfere with the rowing or peddling activity.