Angular Speed with arduino

#include "HX711.h"
#define DOUT 2
#define CLK 3

HX711 cell(3,2);

int pinLed = 13;
int buttonPin = 9;
long zero = 0;
String stringa;
char c;
unsigned long referenceMillis = 0;
unsigned long currentMillis = 0;
unsigned long previousMillis = 0;
unsigned long targetMillis = 0;
int potentiometer = 0;
int potentiometer1 = 0;
int potentiometer2 = 0;
long lecture = 0;
long tension = 0;
const float LSB = 0.000000196;
const float sensitivity = 1.834862385;
float torque;
int value;
const int supply = 5;
float angrad;
float angRad;
float power;
float velang;


void setup() {
  
  Serial.begin(9600);
  pinMode(pinLed,OUTPUT);
  pinMode(buttonPin,INPUT);
  Serial.println("CLEARDATA");
  Serial.println("LABEL,Time,TIME,TORQUE,VELANG,POWER");

}

void loop() {
  
  delay(10000);
  
  digitalWrite(pinLed,HIGH);
  
  zero = read_avarage(byte times = 10);
  potentiometer = analogRead (A0);
  
  if(Serial.available()){
    stringa="";
    do{
      if(Serial.available()){
        c=Serial.read();
        if(c != "\n")
          stringa+=c;
      }
    }while(c != "\n");

   if((stringa == "start")){
        
        digitalWrite(pinLed,LOW);
        referenceMillis = millis();
        
    while ((digitalRead(buttonPin)==LOW) || (referenceMillis <= 3600000)) {

        currentMillis = millis();

        if ( currentMillis - previousMillis >= 12,5 ){
            
            previousMillis = currentMillis;
            
            lecture = cell.read() - zero;
            tension = LSB*lettura;
            torque = tension/sensitivity;
            potentiometer1 = analogRead (A0);
            potentiometer2 = potentiometer1 - potentiometer;
            value = map(potentiometero2,0,1023,0,5);
            angrad = (320*value)/supply;
            angRad = map(angrad,0,360,0,6.283);
            targetMillis = (currentMillis - referenceMillis)*0,001;
            velang = angRad/targetMillis;
            power = torque*velang;
            
            Serial.print("DATA,TIME,");Serial.print(currentMillis);Serial.print(",");Serial.print(torque);Serial.print(",");Serial.print(velang);Serial.print(",");Serial.print(power);

        }

      }
   
   digitalWrite(pinLed,HIGH);
   delay(1000);
   digitalWrite(pinLed,LOW);
   delay(1000);
   digitalWrite(pinLed,HIGH);
   delay(1000);
   digitalWrite(pinLed,LOW);
   delay(1000);
   
   }
   
   }

}

I'm trying to analyse the power develepoed by a leg during an exercise in a gym. The problem is similar to the one of a heat engine but the the parameter are low with respect to the ones of an engine