The study investigated the effect of varying pole weights on energy expenditure, upper limb muscle activation and on forces transmitted to the poles during Nordic walking (NW). Twelve women [age = 21 (2) years, body mass = 60.8 (6) kg, height = 1.71 (0.06) m] participated in five 7-min walking tests randomly chosen without poles (W), with normal NW poles (NW) or with added masses of 0.5 kg (NW + 0.5) 1.0 kg (NW + 1.0) or 1.5 kg (NW + 1.5) at a speed of 2 m s(-1). Heart rate (HR), relative oxygen uptake ([Formula: see text]), blood lactate (La) and rate of perceived exertion (RPE) were registered along with surface EMG (SEMG) from biceps brachii, triceps brachii, trapecius and deltoideus muscles. Inbuilt force transducers measured reaction forces along the long axes of the poles. NW + 0.5 and NW + 1.5 showed significant increases for [Formula: see text] and RPE compared with W (p < 0.05) but with no respective differences within NW. SEMG revealed higher activation of biceps brachii for all NW tests plus added masses compared to W (p < 0.05). Additionally the activation of biceps brachii was higher for NW + 1.5 compared to NW (p < 0.05). The contribution to overall activation duration of triceps brachii became lower but increased for biceps brachii with heavier poles. The increased energy expenditure during NW can be attributed to intensified muscle activation during forward swing of the poles. Heavier poles have no effect on energy expenditure compared to NW with usual poles but enhance muscular activity. Since there are no benefits concerning physiological and biomechanical parameters we do not recommend the use of heavier NW poles.