Neither is actually "better". All exercise accessories have their uses. Weights require more muscles in use to maintain proper form, while the bands and tubes are easier to use in targeting specific muscles. Bands and tubes also have the advantage of being somewhat adjustable in resistance just by changing length. To change weights in dumbbells, you either need another set of dumbbells, or extra plates for those which use plates. Dumbbells, however, do offer a much greater range of available weights, particularly at the high end, making them more useful in strength training. Bands and tubes are generally used in resistance training exercises.
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